CLASS XII - SCIENCE STREAM

BIOLOGY SUMMER BREAK HOLIDAY HOME WORK

2019-2020

CLASS XII

1. Attempt all the questions given in the selected assignments in the note book and draw

diagrams wherever necessary.

2. Work out a Project on any relevant topic for CBSE examination and gather necessary

information including medical reports for diseases(if chosen).

3. Make a PowerPoint presentation along with a poster on a A-3 size thick sheet on the topics

allotted to you from the Unit III.Ecology and Envionment.

4. The students will write practicals of first term and second term in practical notebook with

diagrams.

5. The students will revise the following units for Periodical Test I scheduled on 5 July 2019.

UNIT I. Reproduction

UNIT II. Genetics and Evolution

CLASS XII

UNIT VI. GENETICS AND EVOLUTION

CHAPTER 5. PRINCIPLES OF INHERITANCE AND VARIATION

ASSIGNMENT

VSA

1. The egg of an animal contains 10 chromosomes, of which one is X-chromosome. How many

autosomes would there be in the karyotype of this animal?

2. A haemophilic man marries a normal homozygous woman. What is the probability that their

daughter will be haemophilic?

SA

3. During a monohybrid cross involving a tall plea plant with a dwarf pea plant, the offspring

populations were tall and dwarf in equal ratio. Work out a cross to show how it is possible.

4. When a tall pea plant was selfed, it produced one-fourth of its progeny as dwarf. Explain with

the help of a cross.

5. How would you find genotype of a tall pea plant bearing white flowers? Explain with the help of

a cross. Name the type of cross you would use.

6. With the help of one example, explain the phenomena of co-dominance and multiple allelism in

human population.

7. Explain pleiotropy with the help of an example.

8. Who proposed chromosomal theory of inheritance? Point out any two similarities in the

behaviour of chromosomes and genes.

9. In a dihybrid cross white eyed, yellow bodied female Drosophila crossed with red eyed, brown

bodied male Drosophila produced in F2 generation, 1.3 per cent recombinants and 98.7 per cent

progeny with parental type combinations. This observation of Morgan deviated from Mendelian

F2 phenotypic dihybrid ratio. Explain giving reasons, Morgan’s observations. 10. How does the gene ‘I’ control ABO blood groups in humans? Write the effect the gene has on

the structure of red blood cells.

11. Differentiate between ‘ZZ’ and ‘XY’ type of sex-determination mechanisms.

12. Recently a baby girl has been reported to suffer from haemophilia. How is it possible? Explain

with the help of a cross.

LA

13. (a) State and explain the law of dominance as proposed by Mendel.

(b) How would phenotype of monohybrid F1 and F2 progeny showing incomplete dominance in

Snapdragon and co-dominance in human blood group be different from Mendelian monohybrid

F1 and F2 progeny? Explain.

14.(a) A garden pea plant bearing terminal, violet flowers, when crossed with another pea plant

bearing axial, violet flowers, produced axial, violet flower and axial, white flowers in the ratio of 3:1.

Work out the cross showing the genotypes of the parent pea plants and their progeny.

(b) Name and state the law that can be derived from this cross and not from a monohybrid

cross.

CLASS XII

UNIT VI. GENETICS AND EVOLUTION

CHAPTER6.MOLECULAR BASIS OF INHERITANCE

ASSIGNMENT

VSA

1. How many base pairs would a DNA segment of length 1.36 mm have?

2. Write the role of histone protein in packaging of DNA in eukaryotes.

3. Name the enzyme involved in the continuous replication of DNA strand. Mention the polarity of

the template strand.

4. At which ends do ‘capping’ and ‘tailing’ of hnRNA occur, respectively.

SA

5. It is established that RNA is the first genetic material. Explain giving three reasons.

6. Why is DNA considered a better hereditary material than RNA?

7. (a) A DNA segment has a total of 1000 nucleotides, out of which 240 of them are adenine

containing nucleotides. How many pyrimidine bases this DNA segment possesses?

(b) Draw a diagrammatic sketch of a portion of DNA segment to support your answer.

8. (a) Why did Hershey and Chase use radioactive sulphur and radioactive phosphorus in their

experiment?

(b) Write the conclusion the scientists arrived at after completing the experiment.

9. Answer the following questions based on Meselson & Stahl’s experiment: a) Write the name of the chemical substance used as a source of nitrogen in the

experiment by them.

b) Why did the scientists synthesise the light & the heavy DNA molecules in the organism

used in the experiment?

c) How did the scientists make it possible to distinguish the heavy DNA molecule from the

light DNA molecule? Explain.

d) Write the conclusion the scientists arrived at after completing the experiment.

10. The base sequence in one of the strands of DNA is TAGCATGAT.

i. Give the base sequence of its complementary strand.

ii. How are these base pairs held together in a DNA molecule?

iii. Explain the base complementarity rules. Name the scientist who framed this rule.

11. (a) Name the scientist who called tRNA an adapter molecule.

(b) Draw a clover leaf structure of tRNA showing the following:

i. Tyrosine attached to its amino acid site.

ii. Anticodon for this amino acid in its correct site (codon for tyrosine is UCA).

(c) What does the actual structure of tRNA look like?

LA

12. The average length of a DNA double helix in a typical mammalian cell is approximately 2.2

metres and the dimension of the nucleus is about 10 -6

m.

a) How is it possible that long DNA polymers are packed within a very small nucleus?

b) Differentiate between euchromatin and heterochromatin.

c) Mention the role of non-histone chromosomal protein.

13. (a) How did Griffith explain the transformation of R-strain(non-virulent) bacteria into S-

strain(virulent)?

(b) Explain how Macleod, McCarty and Avery determined the biochemical nature of the

molecule responsible for transforming R-strain bacteria into S-strain bacteria.

14. (a) What did Meselson and Stahl observe when

i. they cultured E. coli in a medium containing 15

NH4Cl for a few generations and

centrifuged the content?

ii. they transferred one such bacterium to the normal medium of NH4Cl and cultured for 2

generations?

(b) What did Meselson and Stahl conclude from this experiment? Explain with the help of

diagrams.

(c) Which is the first genetic material? Give reasons in support of your answers.

15. (a) Draw a labelled diagram of a “replicating fork” showing the polarity. Why does DNA replication occur within such ‘forks’?

(b) Name two enzymes involved in the process of DNA replication, along with their properties.

16. (a) Write the specific features of the genetic code AUG.

(b) Genetic codes can be universal and degenerate. Write about them, giving one example of

each.

(c) Explain the aminoacylation of the tRNA.

17. Draw a labelled schematic structure of a transcription unit. Explain the function of each

component in the unit in the process of transcription.

18. (a) What is an operon?

(b) Explain how a polycistronic structural gene is regulated by a common promoter and a

combination of regulatory genes in a lac-operon.

19. Explain the steps of DNA fingerprinting that will help in processing of the two blood samples A

and B picked up from the crime scene.

20. Explain Human Genome Project.

****

CLASS XII

UNIT VI. GENETICS AND EVOLUTION

CHAPTER 7. EVOLUTION

ASSIGNMENT

VSA

1. Identify the examples of homologous structures from the following:

a) Vertebrate hearts

b) Thorns in Bougainvillea & tendrils of Cucurbita.

c) Food storage organs in sweet potato & potato.

2. Why are the wings of a butterfly and of a bat called analogous?

SA

3. Describe the experiment that helped Louis Pasteur to dismiss the theory of spontaneous

generation of life.

4. Convergent evolution and divergent evolution are the two concepts explaining organic

evolution. Explain each one with the help of an example.

OR

Differentiate between divergent & convergent evolution. Give one example of each.

5. Branching descent & natural selection are the two key concepts of Darwinian theory of

evolution. Explain each concept with the help of a suitable example.

6. “Post-industrialization, the population of melanised moth increased in England at the expense of

white-winged moths.” Provide explanation. 7. How is Darwin’s concept of evolution different from that of de Vries?

8. What does the following equation represent? Explain.

p2+2pq+q

2=1

9. Anthropogenic action can hasten the evolution. Explain with the help of a suitable example.

LA

10. (a) Name the primates that lived about 15 million years ago. List their characteristic features.

(b) (i) Where was the first man-like animal found?

(ii) Write the order in which Neanderthals, Homo habilis & Homo erectus appeared on

earth. State the brain capacity of each one of them.

(iii) When did modern Homo sapiens appear on this planet?

11. (a) Write the Hardy-Weinberg Principle.

(b) Explain the three different ways in which natural selection can affect the frequency of a

heritable trait in a population with help of graphs.

****

CHEMISTRY

SUMMER HOLIDAY HOMEWORK

Complete the practical file

Make an investigatory project experiment file (topic to be selected from CBSE

website)

Revise the concepts taught for first periodical examination and complete the

assignments on topic

UNIT TITLE

1 SOLUTIONS

2 ELECTROCHEMISTRY

3 CHEMICAL KINETICS

4 SURFACE CHEMISTRY

5

GENERAL PRINCIPLES AND PROCESS OF ISOLATION OF

ELEMENTS

6 P-BLOCK ELEMENTS

7 d AND f BLOCK ELEMENTS

8 COORDINATION COMPOUNDS

ASSIGNMENT

Solutions

1. A solution is prepared by dissolving 10g of solute in 200g of water. it has a vapour pressure of 31.84mm Hg at 308 K. calculate the molar mass of the solute. (180)

2. What mass of NaCl must be dissolved in 65g of water to lower the freezing point of water by 7.50C? the freezing point depression constant for water is 1.860C/m. Assume van't Hoff factor for NaCl is 1.87 (8.177g)

3. State how does Raoult's law Become a special case of Henry's law. 4. On dissolving 19.5 g of CH2FCOOH in 500g of water, a depression of 10.C in

freezing point of water is observed. Calculate the van't Hoff factor and dissociation constant of fluoro Acetic Acid. given Kf= 1.86 K Kg/mol (2.83X10-3)

5. Heptane and Octane form an ideal solution at 373K . the vapour pressure of the pure liquids and this temperature are 105.2KPa and 46.8 KPa , respectively. if the solution contains 25g of heptane and 28.5 g of Octane, calculate

(i) vapour pressure exerted by heptane (ii) (vapour pressure exerted by solution (iii) mole fraction of obtain in vapour phase

6. A 0.1539 molal aqua solution of Cane sugar ( molecular mass= 342g/mol) has a freezing point of 271 k while the free of pure water is 273.15k. what will be the freezing point of an aqueous solution containing 5g of glucose( molecular mass= 180g/mol) per 100g of solution?

7. Give reason for the following: (a) When 30ml of ethyl alcohol and 30ml of water are mixed, the volume of resulting solution is more than 60ml

(b) Copper is conducted as such file copper sulphate is conducting only in molten state or in aqueous state

8. State Henry's law for solubility of a gas in a liquid. explain the significance of Henry's law constant (KH).Same temperature, hydrogen is more soluble in water than helium. which of them will have a higher value of Henry's law constant and why?

9. (a) Define crops and explain briefly minimum boiling azeotrope by taking suitable example (b) The vapour pressure of pure liquids A and B are 450mm and 700mm of Hg respectively at 350K . calculate the composition of liquid mixture total vapour pressure is 600mm of Hg. also find the composition of the mixture in vapour phase.

10. (a) Derive the relationship between relative lowering of vapour pressure and mole fraction of the volatile liquid. (b) (i) Benzoic acid completely dimerizes in Benzene. what will be the vapour pressure of a solution containing 61 gram of benzoic acid per 500g benzene when the vapour pressure of pure benzene at the temperature of experiment is 66. 6 torr? (ii) What would have been the vapour pressure in the absence of dimerization? (iii) Derive a relationship between mole fraction and vapour pressure of a component of an ideal solution in the liquid phase and vapour phase.

ASSIGNMENT

Electrochemistry

1. How much charge in Faraday's is required for the reduction of 1mol of Al3+ to Al? 2. How may the conductivity of an intrinsic semiconductor be increased? 3. Express the relation between conductivity and molar conductivity of a solution

held in a Cell. 4. What is meant by limiting molar conductivity? 5. Why is equilibrium constant K related to EO

cell and not Ecell ? 6. How does the molar conductivity of KCl solution vary with increasing

concentration? 7. How does fuel cell operate? 8. Which type of metal can be used in cathodic protection of iron against rusting? 9. How does cathodic protection of iron operate? 10. Electrolysis of KBr (aq) gives Br2 at anode but of KF (aq) does not give F2

. give reason for disparity in behaviour. 11. Calculate the time to deposit 1.27g of copper at cathode when a current of

2A was passed through the solution of CuSo4. 12. (a) Following reactions occur at cathode during the electrolysis of aqueous

copper (II) chloride solution : Cu2+ (aq) + 2e- ---> Cu (s) EO= +0.34V H+

. (aq) + e- ---> ½ H2 (g) EO= 0.00V

On the Basis of their standard reduction electrode potential (EO) Values, which reaction is feasible at the cathode and why?

(b) State kohlrausch Law of independent migration of ions.Write its one application.

13. Express the relation among cell constant, resistance of the solution in the cell and conductivity of the solution. how conductivity of a solution related to its conductivity?

14. Given the standard electrode potential of metals are: K+ /K =-2.93 V, Ag+/Ag = 0.80V,

Fe2+/Fe= -0.44V

Arrange these metals in an increasing order of their reducing power. 15. Two half reactions of an electrochemical cell are given below :

MnO4- (aq) + 8H+ (aq) + 5e- ---> Mn+2 (aq) + 4H2O (aq) E0=1.51V

Sn+2 (aq) ----> Sn+4 (aq) + 2e- Eo=0.15V

Construct the Redox reaction equation from the two half reactions and calculate the potential from the standard potentials and predict if the reaction is reactant or product favoured.

16. What type of cell is a Lead Storage battery? write the anode and the cathode reactions and the overall cell reaction occurring in the use of a Lead Storage battery. 17. The molar conductivity of a 1.5M solution of an electrolyte is found to be 138.9Scm2mol-1. calculate the conductivity of this solution.

ASSIGNMENT

CHEMICAL KINETICS

1. Define the rate of reaction. Write two factor that affect the rate of reaction. 2. Rate constant k for first order reaction has been found to be

2.54x103sec1.Calculate its three fourth time. 3. The rate constant for a first order reaction becomes 6 times when the temperature

is raised from 350K to 400K. Calculate the activation energy for the reaction. 4. Half life of a first order reaction is 5x104sec . What percentage of the initial

reactant will react in 2 hours? Calculate. 5. The rates of most reactions doubled when the temperature is raised from 298K to

308K.Calculate activation energy of such a reaction. 6. Define the following term:

(a)activation energy, (b)rate constant, (c) order of reaction

7. Write two differences between order of reaction and molecularity of reaction 8. Why does the rate of a reaction not remain constant throughout the reaction

process. 9. The rate of a reaction increases to four times when the prevailing temperature is

raised from 300K to 320K. calculate the energy of activation of this reaction assuming that it does not change with temperature

10. Illustrate graphically the effect of catalyst on activation energy.

ASSIGNMENT

SURFACE CHEMISTRY

1. A delta is formed at the meeting point of water and river water, why? 2. What is type of charge on AgI colloidal SOL formed when AgNO3 is added to

KI solution? 3. Write the dispersed phase and dispersion medium of paints 4. Of physisorption or chemisorption, which has a higher enthalpy of adsorption? 5. Define peptization 6. Define what is tyndall effect and what is shape selective catalysis. 7. Explain the term dialysis with a suitable example 8. What are emulsions? how are they classified? state and application of emulsification. 9. Explain freundlich adsorption isotherm.

10. Show with the help of a diagram arrangement of stearate ions inside the bulk of water( ionic micelle) at critical micelle concentration of soap.

11. Taking two example of heterogeneous catalytic reaction, explain a how a heterogeneous catalyst helps in the reaction.

12. What is the role of diffusion in heterogeneous catalysis. 13. Absorption, if spontaneous, is exothermic. Explain. 14. Why does leather get Hardened after tanning? 15. How does it become possible to cause artificial rain by spraying silver iodide on the

clouds

ASSIGNMENT

GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

1. (a) Name the method used for removing gangue from sulphide ore.

(b) How wrought iron different from steel?

2. Which methods are usually employed for purifying the following metals:

(a) Nickel

(b) Germanium

3. Describe the principle involved in each of the following processes :

(a) Mond’s process for refining of nickel. (b) Column chromatography for purification of rare elements.

4. Describe the principle controlling each of the following processes :

(a) zone refining of metals.

(b) Electrolytic refining of metals.

5. How is chemical reduction different from electrolytic reduction ? Name a metal each which is

obtained by

(a) electrolytic reduction

(b) chemical reduction

6. How can u obtain pure alumina from bauxite ore? Write the chemical equations involved.

7. Describe the role of the following:

(a) NaCN in the extraction of silver from a silver ore.

(b) Cryolite in the extraction of aluminium from pure alumina.

8. Give two requirements for vapour phase refining.

9. How do we separate two sulphide ores by froth floatation method ? Explain with an example.

10. Which method is used for refining of Zr and Ti ? Explain with equation.

ASSIGNMENT

THE P BLOCK ELEMENTS

1. Write the oxo acids of sulphur and chlorine and arrange them in increasing order of

acidity.

2. Draw the structure of the following :

3. (a) BrO4-

(b) XeF4

(c) XeF2

(d) SF6

(e) IF5

(f) XeO3

(g) XeOF4

(h)red phosphorous

(i) white phosphorous

(j) SF4

(k) XeOF2

4. Give reason for the following :

(a) Sulphur vapour is paramagnetic

(b) Ammonia has greater affinity for protons than phosphine

(c) The negative value of electron gain enthalpy of fluorine is less than that of

chlorine.

(d) SF6 is much less reactive than SF4

(e)Of the noble gas, onlu xenon is known to form well establishes chemical

compounds.

(f) Solid PCl5 is an ionic compound.

(g) Most of the reactions of fluorine are exsothermic

(h) Ozone is thermodynamically unstable

(i) Why nobel gases have very low boiling points?

(j) Why does fluorine not play the role of a central atom in interhalogen compounds?

(k) Oxygen is gas but sulphur is a solid

(l) Halogens are coloured.why?

(m) Phosphorous have greater tendency for catenation than nitrogen.

(n) Helium used in diving apparatus.

(o) Fluorine does not exhibit positive oxidation state

(p) Oxygen shows catenation behavior less than sulphur

(q) Acidic character increases from HF to HI.

(r)There is large difference between the melting and boiling points of oxygen and

sulphur

(s) Nitrogen does not form pentahalides

(t)Solid phosphorous pentachloride behaves as ionic compound

(u) Halogens are strong oxidizing agents.

(v)The stability of +5 oxidation state decreases down the group in group 15 of the

periodic table. (w) NF3 is an exothermic compound but NCl3 is endothermic

compound.

(x) CLF3 molecule has T shaped structure and not a trigonal planar one.

ASSIGNMENT

THE d AND f BLOCK ELEMENTS

1. Explain : (a) Copper atom has completely filled d-orbitals in its ground state but it is a

transition element

(b) Why is zinc not regarded as a transition element?

(c) Why is Bi (v) a stronger oxidant than Sb (v)

(d)Why is Ce+4

in aqueuous solution a good oxidizing agent ?

(e) Why is third ionisartion energy of manganese unexpectedly high?

2. Write one similarity and one difference between the chemistry of lanthanoids and that of

actinoids.

3. Transition metal show high melting points. Why?

4. Account for the following :

(a) Cu+ is unstable in an aqueuous solution

(b) Transition metals form complex compounds

(c) Actinoids contraction is greater than lanthanoid contraction.

(d) transition metals form coloured compounds.

(e) Highest fluoride of Mn is MnF4 whereas the highest oxide is Mn2O7.

(f) Transition metals and their compounds show catalytic properties.

(g)The transitionnmetals are well known for the formation of interstitial compounds.

(h) The largest number of oxidation states are exhibited by manganese in the first series of

transition elements.

(i) All scandium salts are white ?

(j) the first ionization enthalpies of 5d transition elements are higher than those of the 3d and

4d transition elements in respective groups?

(k)reactivity of transition elements decreases almost regularly from Sc to Cu.Explain.

(l) The halides of transition elements become more covalent with increasing oxidation state.

(m) Size pf trivalent lanthanoid cations decreases with increase in the atomic number.

(n) Chemistry of all lanthanoids is similar

(O) Transition metal flourides are ionic, whereas bromides and chlorides are usually covalent

in nature.

ASSIGNMENT

COORDINATION COMPOUNDS

1. Write two differences between a double salt and a coordination complex with the help of an

example.

2. Mention the main postulates of Werner’s Theory.

3. Define (a) Homoleptic and (b) Heteroleptic complexes with the help of one example of each.

a. Identify the ligand involved and

b. Oxidation state of copper metal.

4. Are the bidentate ligands same as the amibidentate ligands? Justify with one example.

5. Calculate the magnetic moments of the following complexes :

(i) [Fe(CN)6]4–

(ii) [CoF6]3–

6. Explain the following

(a) All octahedral complexes of Ni2+

must be outer orbital complexes.

(b) NH4+ ion does not form any complex.

7. What type of structural isomerism is represented by the following pairs :

(a) [Mn(CO)5SCN] and [Mn(CO)5NCS]

(b) [Co(NH3)5NO3] SO4 and [Co(NH3)5SO4] NO3

8. How complex compounds are applicable in (a) electroplating of silver, gold or other noble metals

(b) in photography.

9. Mention two limitations of crystal Field Theory.

10. Derive a relationship between stepwise stability constants and overall stability constant of a

complex in the solution. How overall stability constant varies with dissociation equilibrium

constant?

11.. Explain as to how the two complexes of nickel [Ni(CN)4]2–

and Ni(CO)4 have different structures

but do not differ in their magnetic behaviours. (At. no. of Ni = 28).

12. Draw the structures of geometrical isomers of the coordination complexes –

[Co(NH3)3Cl3] and [CoCl2(en)2]+

PHYSICS

SUMMER HOLIDAY HOME ASSIGNMENT

The students will complete the Assignments on

1. Electrostatics

2. Current electricity

3. Ray optics

4. Electronic Devices

Complete the practical file and Activity file .

Make a working project/investigatory project on one topic of physics as discussed .

Revise the concepts taught for the periodical examination.

CURRENT ELECTRICITY

CHAPTER -3

CLASS XII

PHYSICS

Q1 A resistance wire is stretched to double its length . What will be its new resistance and

resistivity?

Q2 Name two devices with negative value of temperature coefficient.

Q3 Draw resistivity vs temperature graphs for copper,nichrome and thyristor.

Q4The plot of the variation of potential difference across a combination of three identical

cells in series, versus current is as shown below. What is the emf of each cell if on the y-axis

the line cuts at 6V on y-axis and 1A on x-axis ?

Q5 potentiometer wire is of 1m length is connected to a standard cell E1=3V.. Another cell E2

of emf 1.5 V e.m.f. is used in the secondary circuit, the balance point is found to be at 60 cm.

On replacing this cell and using a cell of unknown e.m.f., the balance shifts to 80 cm. (i)

Calculate unknown e.m.f. of the cell. (ii)

Explain with reason, whether the circuit works, if the driver cell is replaced by a cell of e.m.f.

1 V. (iii) Does the high resistance R, used in the secondary circuit affect the balance point ?

Justify your answer.

Q6 A resistance 4Ω is connected to one of the gaps in a

metre bridge, which uses a wire of length 1 m. An unknown resistance X> 4Ω is connected in the other gap as shown in the figure. The balance point is noticed at ‘ l’ from the positive end of the battery. On interchanging R and X, it is found that the balance point

further shifts by 20 cm (away from end A). Neglecting the end correction, calculate the

value of unknown resistance X used.

Q7 Calculate the steady state current through the circuit shown in the figure given below.

The internal resistance of the battery is negligible and capacitance of the capacitor is 0.5µF.

Q8 Find the equivalent resistance in the given figure:

Q9 A cell of emf E and internal resistance r are connected across variable external resistance

R. Plot the variation of a)E with R b) V with R

Q10Two identical slabs are arranges as shown in the given figure below:

Find the ratio of the resistance of these two combinations?

ELECTRIC POTENTIAL AND CAPACITANCE

CHAPTER -2

CLASS XII

PHYSICS

Q1 Draw graphical variation of electric potential due to a uniformally charged

a) Spherical shell b) Solid sphere

Q2 Three point charges +Q,-2Q and -3Q are placed at the vertices of an equilateral triangle of

side l.If these charges are displaced to the mid points A1,B1 and C1 respectively, calculate the

amount of work done in shifting the charges to the new location.

Fig:

Q3 Four point charges are placed at the four corners of the square of side l. The charges are of

magnitude +q,-q,+q and –q respectively on the corners ABCD . What is the electric field and

electric potential at the centre of the square?

Q4 A 500 mC charge is at the centre of a square of side 10 cm. Find the work done in

moving a charge of 10 mC between two diagonally opposite points on the square.

Q5 Derive the expression for the electric potential at any point along the axial line of an

electric dipole .

Q6 Find the equivalent capacitance for the following configuration of capacitors in fig 1 .

Q7 In fig 2 the dielectric constants are k1 ,k2 and k3 respectively. Find equivalent C.

fig 1 fig2

Q8 A charge of 20 µC produces an electric field. Two points are10cm and 5 cm from this

charge. Find the values of potentials at these points and also find the amount of work done

to take an electron from one point to other.

Q9 Three charges –q, Q and –q are placed at equal distances on a straight line. If the

potential energy of the system of three charges is zero, then what is the ratio of Q: q?

Q10 A parallel plate capacitor having plate area 100 cm2 and plate separation 1 mm holds

a charge of 0.12µC, when connected to a 120V battery. Find the dielectric constant of the

material between the plates.

Q11 The given graph shows the variation of charge q verses potential difference V for two

capacitors C1 and C2. The two capacitors have same plate separation but the plate area of

C2 is double than that of C1. Which of the two graphs P and Q corresponds to capacitors

C1 and C2 and why?

Fig:

Q12 Find the equivalent capacitance of the network shown in the figure, when each

capacitor is of 1 µF. When the ends X and Y are connected to a 6V battery, find out

(i) The charge and

(ii) the energy stored in the network.

Fig:

ASSIGNMENT-SOLID AND SEMICONDUCTOR

CLASS XII

Q1 In the following diagram, pn junction is forward or reverse biased?

Q2 Draw the output wave form from

AND Gate and NOR Gate. Also draw the output wave form from the combination of the gates

given in (A) and (B).

Q3 Name the important process that occurs during the formation of a pn junction. Explain

briefly, with the help of a suitable diagram, how a pn junction is formed. Define the termd

“barrier potential”.

Q4 Explain briefly the using the necessary circuit diagram, the three basic processes which

take place to generate the emf in a solar cell when light falls on it. Draw the I-V

characteristics of a solar cell. Write two important criteria required for the selection of

material for solar cell fabrication.

Q5 write the truth table for the given logic gates.

Q6The graph of the potential barrier versus width of depletion region for an unbiased diode is shown

in A. In comparison to A, graphs B and C are obtained after biasing the diode in different ways.

Identify the type of biasing in B and C and justify your answer.

Fig:

Q7 A change of 0.2 mA in the base current causes a change of 5 mA in the collector current for a

common emitter amplifier.

a) Find the ac current gain of the transistor.

b) Ii) If the input resistance is 2KΩ and its voltage gain is 75, calculate the load resistor used in the circuit.

Q8 Give reasons:

a) The Zener Diode is fabricated by heavily doping both p and n sides of the junction.

b) A photodiode, when used as a detector of optical signals is operated under reverse bias.

c) The band gap of the semiconductor used for fabrication of visible LED’s must be atleast 1.8eV. Q9 A) Distinguish between an intrinsic semiconductor and a p-type semiconductor. Give reason why a

p-type semiconductor is electrically neutral, although n h >> n e .

Q10 Draw a labelled diagram of common emitter amplifier using npn transistor.

ELECTROSTATICS

CHAPTER -1

CLASS XII

PHYSICS

Q1 Two identical metallic spheres are equal masses. One is given positive charge Q coulomb and the

other an equal negative charge by friction. Are their masses after charging equal?

Q2 Can two ball having same kind of charge on them attract each other?

Q3 What does Q1+Q2 =0 signfy?

Q4 Graphically , represent the variation of electric field due to a point charge Q with

a) Magnitude of the charge

b) Distance r

c) Distance 1/r2

Q5 Two small identical electrical dipoles AB and CD , each of dipole moment ‘p’ are kept at an angle of 120

0 as shown in the figure.

a) What is the resultant dipole moment of this combination?

b) If this system is subjected to electric field (E) directed along + X direction , what will be the

magnitude and direction of the torque acting on this ?

Fig:

Q6 Two point charges of 2 µC each of opposite signs are placed 10cm apart. Calculate the electric field

at a point distant 10 cm from the midpoint on the axial line of the dipole.

Q7Four point charges are placed at the corners of a square of side 2cm. find the electric field at the

centre of the square ,if the charges are Q=0.02µC. The charges are placed as on A: -2Q ,B: +2Q,C: -Q &

D : +Q.

Q8. A non conducting semicircular rod is given some +ve charge on the upper half portion and –ve

charge on the lower half portion. What is the direction of net electric field at the point p , which lies

on the centre of the diameter of the semicircular rod.

Q9 Show diagrammatically the orientation of the dipole in the field for which the torque is

1) Maximum

2) Half the maximum value

3) Zero

Q10 Trace the path of an electron and a proton, if both enter a uniform electric field, with the same

velocity, perpendicular to the field.

Q11 two point charges 3µC and -3µC are located 20cm apart in vacuum.

a) Calculate the electric field at the mid point O on the line AB joining the two charges.

b) What is the force experienced by a negative test charge of magnitude 1.5 x 10 -9

C placed at

this point.

Q12 An infinite line charge produces a field of 9 x 10 4

N/C at a distance of 2 cm. Calculate the linear

charge density.

Q13 In the given figure, find the

a) Magnitude and direction of the net force acting on the charge at O.

b) Sign and magnitude of the charge at G so that the charge at O remains in equilibrium.

Q14 Figure shows an electric dipole lying in a uniform electric field.Find the

(i) dipole moment

(ii) torque acting on dipole

(iii) potential energy of dipole

Q15 Imagine a cube of side 20cm kept in the space, as shown in figure.

If the components of electric fields are :Ex = 500 x ½ ,Ey=0 and Ez =0

Find the total electric flux through the cube and charge enclosed.

Fig:

ASSIGNMENT-RAY OPTICS

CLASS XII

Q1 Does the apparent depth of a tank change if viewed obliquely?

Q2 Critical angle is different for different colour of light. Is this statement true?

Justify.

Q3 The line AB in the ray diagram represents a lens. State whether the lens is

convex or concave.

Fig:

Q4 It is difficult to view through fog. Why?

Q5 You are given the following three lenses, Which two lenses will you use as an

eyepiece and as an objective to construct an astronomical telescope?

LENSES POWER APERTURE(IN cm)

L1 3D 8

L2 6D 1

L3 10 D 1

Q6 How does the focal length of a lens change when red light incident on it is

replaced by violet light ? Give reason for your answer.

Q7 A convex lens made up of glass of refractive index 1.5 is dipped , in turn, in

i) a medium of refractive index 1.65, ii) a medium of refractive index 1.33.

a) Will it behave as a converging or a diverging lens in the two cases?

b) How will its focal length change in the two media?

Q8 Double convex lenses are to be manufactured from a glass of refractive

index 1.55, with both the faces of the same radius of curvature. What is the

radius of curvature required if the focal length is to be 20 cm?

Q9 Compare the refractive indices in the given figure:

Q10A ray PQ incident on the refracting face BA is refracted in the prism BAC

as shown in the figure and emerges from the other refracting face AC as RS

such that AQ=R. If the angle of prism A = 60 0

and refractive index of material

of prism is , calculate ϴ.

Q11 Calculate the value of ϴ, for which light incident normally on face AB

grazes along the face BC. Given that: µg=3/2, µ w=4/3

HOLIDAY HOMEWORK CLASS XII MATHS

CLASS XII

SUBJECT : ENGLISH

HOLIDAY HOMEWORK

Revise the syllabus covered in the class.

Prepare an interesting PPT on any chapter from Flamingo or Vistas.

Prepare an invitation card (formal) on the occasion of your parents’ 25th

Wedding anniversary.

Prepare at least eight ‘ Reference to the context’ based questions on the chapters ‘ The last lesson’, ‘Deep water’ and ‘Lost Spring’ in your notebook

Prepare notes of the chapter ‘The Last lesson’ by Alphonse Daudet and ‘The Tiger king’ by Kalki, using headings and sub-headings in the notebook. Also

write a summary of these lessons in about 100 words.

Paste ten Classified advertisements (from newspaper) in the notebook.

'India is a land of diversity‟. As the Head boy/girl of your school, write a

speech to be delivered in the morning assembly highlighting the fact that we

need to live in harmony despite our differences, and can achieve unity in

diversity.

'The policy of reservation of seats for admission to professional courses

needs to be revisited.’ Write an article on the topic expressing your strong opinion on the statement. You are Shiny/ Sumit.

You are Shaurya, staying at South Delhi. You bought a Laptop from “Elite Shop”. The laptop developed a problem within few days of the purchase.

Write a letter to the Sales Manager of the showroom complaining about the

defect and seeking the immediate replacement.

Computer Science

SUMMER HOLIDAY HOMEWORK

1. Project Work

Project for class XII should ensure the coverage of following areas of curriculum:

a. Problem Solving

b. Data Structure

c. Object Oriented Programming in C++

d. Data File Handling

Theme of the project can be

• Any subsystem of a System Software or Tool

• Any Scientific or a fairly complex algorithmic situation. • Business oriented problems like Banking, Library information system, Hotel or Hospital management system, Transport query system

• Quizzes/Games; • Tutor/Computer Aided Learning Systems

The students will make the GUI and files which are required for handling the application. They

will bring a introduction of their project with proper referencing.

2. The practical file should have the practical no’s 1-12 done in their files.

3. Revise the First Periodical Syllabus

Chapter 1:-C++ Revision Tour

Chapter 2:-Basics of OOPS

Chapter 3:- Function Overloading

Chapter 4:- Classes and Objects

Chapter 5:- Constructors and Destructors

Chapter 6:- Inheritance

Chapter 7:- Data File Handling

Chapter 13:- Boolean Algebra

Chapter 14:- Communication and Networking Concepts

4. All the worksheets based on the above chapters should be done in assignment copy.

Class 12 (PHYSICAL EDUCATION)

1- Project file work on the assigned topics.

Volleyball

Basketball

Football

Handball

2- Revise all the topics for the syllabus in periodic test.