half-yearly examination class:xi sub:...

HALF-YEARLY EXAMINATIONCLASS:XI SUB: CHEMISTRY

TIME: 3 Hours M.MARKS:70BLUE PRINT

S.No. UNIT VSA SA I SA II VALUE

BASED LA TOTAL

1Mark

2Marks

3Marks

4Marks

5Marks

1Some Basic concepts of

chemistry 1(1) 1(2) 1(3) - 3(6)

2 Structure of Atom 1(1) - 3(3) - 4(10)

3Classification of Elements

and Periodicity in Properties 1(1) - - 1(5) 2(6)

4Chemical Bonding and

molecular Structure - - 3(3) - 3(9)

5States of Matter: Gases and

Liquids - 1(2) 2(3) - 3(8)

6 Thermodynamics 1(1) 1(2) 2(3) - 4(9)

7 Equilibrium 1(1) - 1(4) 1(5) 3(10)

8 Redox Reactions - 1(2) - 1(5) 1(7)

9 Hydrogen - 1(2) 1(3) - 1(5)

Total 5(5) 5(10) 12(36) 1(4) 3(15) 26(70)

“Value Education with Training”

DAV CENTENARY PUBLIC SCHOOL, PASCHIM ENCLAVE, NEW DELHI - 87


TIME: 3 Hours M.MARKS:70

GENERAL INSTRUCTIONS :All questions are compulsory.

Q. No. 1 – 5 are very short answer question, carrying 1 marks each. Answer these question in one

word or about one sentence each.

Q. No. 6- 10 are short answers questions, carrying 2 marks each. Answer in about 30 words each.

Q. No.11 - 22 are also short answers questions, carrying 3 marks each. Answer in about 40 words

each..

Q. No. 23 is Value Based question carrying 4 marks.

Q No. 24 – 26 are also long answer questions, carrying 5 marks each. Answer these in about 70

words each.

*Use log tables if necessary.

Q.1 If 10 volumes of dihydrogen react with 05 volumes of dioxygen gas, how many volumes of

water will be produced?

Q.2 What is the relationship between De-Broglie wavelength of a matter wave with the velocity of

a microscopic particles .

Q.3 Mention IUPAC name and symbol of element having Aomic Number 127.

Q.4

Q.5 4.

Q.6

Q.7 How will you justify that Hydrogen Peroxide can be used as

(ii) Bleaching Agent.

Q.8

Define the terms Enthalpy of Neutralisation and Bond Enthalpy ?

Zn (s) + 2Ag+ (aq) Zn2+ (aq) + 2Ag (s).

i) which electrode is negatively charged ?

ii) what is the direction of the current ?

Q.10 What will be minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at

300C ?



32- .

(ii) Draw the geometry of BrF3 and Pcl5 molecule.

Q.12 Calculate the wave length & Frequency of light wave whose period is 2.0 x 10 -10 s.

Q.13. Give one example of the following

(i) Ionic Hydride (ii) Covalent Hydride (iii) Interstitial Hydride

( i) What causes temporary and permanent hardness of water ?

( ii) Why H2 2 is stored in wax-lined plastic bottles?

Q.14. What is the wavelength of light emitted when the electron in a Hydrogen atom undergoes

Q.15 Define Hybridisation . Draw the shapes of BeCl2 and Ethyne.

Q.16 (a) Give an example

(b) Calculate temperature of 4.0 mole of a gas occupying 5 dm3 3

K-1 mol-1 ?

Q.17 -1 -1

constant over the temperature range ?

Q.18 Derive the relationship between Cp&C v.

Q.19 Write molecular orbital configuration & Campare Bond- 2 2 .

Q.20

2 gas or NH3 gas.

(ii) What is the importance of a and b in Vander waal gas Equation

Q21 yz& dx2-y2 orbitals.

Q.22 3 + 2HCl CaCl2 +H2 2. Wh 3 is required to react with 25ml of

3

Q.23

,their use for cleaning toilets is very common. However in recent times, bad elements are

using these acids. For example, incidents of Acid throwing on faces ,thereby causing burns

on the face, are being often reported. Balloons filled with acids are thrown on the passers

by on Holi festival.A mixture of Acids is used by the miscreants to cheat women in the name

After reading the above paragraph, answer the following questions.



(i)What values are expressed in the above paragraph

(ii)Which two acids are mixed to dissolve Gold and in what ratio. Name this mixture also.

Q.24. ( a) Find the conjugate acid / base for the following species : F- , HCN, NH3 32-

(b) Calculate the pH of the following solution:0.3 g

of solution.

a) Predict if the solutions of the following salts as neutral ,acidic or basic :

NaCl , NH4 3 2 ,

Effect.

Q.25 (a) Balance the following equations-

3 + H2

4-+ Fe +2 Mn+2 +Fe +3 +H2 -electron method)

(b) Give example of redox reaction which is also a combination reaction.

(a) Balance the following equations-

4- + I - 2 + I2 ( in basic medium by ion-electron method)

(ii) Cr 2 7-

2 Cr +34

-2( in acidic medium by oxidation-No. method)

(b) Give 2 differences in oxidation No. & valency.

Q.26 a)Which one will have lower first ionisation energy- Kr or Xe

b) Which one will have lower electron-

c) Predict the formula of binary compound that would be formed by ( i)element 114 & F

d) write the general configuration of d block element

e) Arrange the following in increasing order of metallic character :B,Al,Mg,K

a)Which one will have lower first ionisation energy- K or Ar

b) Which one will have lower electron-gain enthalpy. Be or B

c) Predict the formula of binary compound that would be formed by ( i)Calcium & Iodine

d) write the general configuration of f block element.

e) Arrange the following in increasing order of non-




TIME: 3 Hours M.MARKS:70MARKING SCHEME

Ans.No VALUE POINTS / SOLUTIONS V.P Wise Marks

1. 10 Volumes of water will be produced. 1

2. . 1

3. Unbiseptium(Ubs) 1

4. 1

5. 4++

4-- 2 1

6. Molar mass Calculations 2

7. 2 2 with Cl2 water(ii)H2 2 2

1+1

8. Correct definitions. 1+1

9. (i) Zn anode carries negative charge.ii) Current flows from silver to zinc in outer circuit.

11

10. At constant temperature, 1V1 2V2

1 barX500dm32X200dm3 Answer P2

11/2+1/2

11. 1+1+1

12. 9 s -1

-2 m ½ +½+½½ +½+½

13. Correct Answer or Correct Causes 3

14.Answ

1+1+1

15. Correct Definition of Hybridisation 12

16 1½+ ½ +1

17. - 111

18. Correct Derivation of Cp-Cv 3

19. 2 2

2 2

½ + ½½ + ½



(iii) N2 2 ½ + ½20 (i)Correct Definition

(ii) NH3 gas due to its low Critical temperature11½+ ½

21(b ) Impossible to measure simultaneously the position and the momentum of microscopic particles with absolute accuracy.

½ + ½

1

1

22. 12

23. a-nown person.

(iii)Being Good Citizen, We should not use Acid or any other harmful chemicals while palying with colours or water or Balloonb- 3 -

1+1(any Two values)½+ ½ +1

24 a) HF , CN- , NH3 3-,

b) Molarity FormulaCalculations

a) NaCl - Neutral , NH4 3 - Acidic

KCN - 2 - Basic b) i) Correct explanation with example

ii) Correct explanation with example

1+11

11

25. a)Balance equations stepwiseb) Correct explanation

1+1+12

26. a (i) Xenonii) Nitrogeniii) UuqF4

(b) (n-1)d1-10 ns1-2

(c) B<K<Mg<Al

a (i) Potassiumii)Berylliumiii) CaI2

(b) (n-2)f1-14 (n-1)d00-1 ns2

11111

11111

***********************************************************





S.No. UNIT VSA SA I SA II VALUE

BASED LA TOTAL

1Mark

2Marks

3Marks

4Marks

5Marks

1 Some Basic concepts of chemistry - - 2(3) - - 2(6)

2 Structure of Atom 1(1) 1(4) 1(5) 3(10)

3Classification of Elements and Periodicity in Properties

1(1) 1(2) 1(3) - - 3(6)

4Chemical Bonding and molecular Structure

1(1) - 1(3) - 1(5) 3(9)

5States of Matter: Gases and Liquids

- 1(2) 2(3) - - 3(8)

6 Thermodynamics 1(1) 1(2) 2(3) - 4(9)

7 Equilibrium - 1(2) 1(3) - 1(5) 3(10)

8 Redox Reactions - - 2(3) - - 2(6)

9 Hydrogen 1(1) 1(2) 1(3) - - 3(6)

Total 5(5) 5(10) 12(36) 1(4) 3(15) 26(70)



SET – TWO [ DEHRADUN REGION]HALF-YEARLY EXAMINATION(2014-15)

CLASS:XI SUB: CHEMISTRYTIME: 3 Hours M.MARKS:70

GENERAL INSTRUCTIONS :All questions are compulsory.Q. No. 1 – 5 are very short answer question, carrying 1 marks each. Answer these question in one word or about one sentence each.Q. No. 6- 10 are short answers questions, carrying 2 marks each. Answer in about 30 words each.Q. No.11 - 22 are also short answers questions, carrying 3 marks each. Answer in about 40 words each..Q. No. 23 is Value Based question carrying 4 marks.Q No. 24 – 26 are also long answer questions, carrying 5 marks each. Answer these in about 70 words each. *Use log tables if necessary. 1) Considering X-axis as the internuclear axis which out of the following will not form a sigma ( )

bond and why? (a) 1s and 1s (b) 1s and 2px (c) 2py and 2py & (d) 1s and 2s.

2)

3) 2 molecule does not exist.

4) Give condition for a reaction to be spontaneous.

5) What do you understand by the term: Hydrogen economy?

6) Explain why: (i)

Chlorine has higher negative electron gain enthalpy than Fluorine.

(ii) Nitrogen has higher first ionization enthalpy than oxygen.

7)

8) Calculate the standard enthalpy of formation of CH3 (l) from the following data :

i)CH3 (l) 2(g) 2(g) + 2H2 (l) r - -1

ii) C (s) 2 (g) 2 (g) c -393 k -1

iii)H2 (g) 2 (g) (l) f - -1

Define the following:

(i) standard enthalpy of combustion (ii) standard enthalpy of atomization

9) 3 from N2 and H2 at

2—2

2—2

3—2 M.

Calculate equilibrium constant.

(II) Give the relationship between Kp and Kc for a general reaction.

10) Define Coal gasification. How can the production of dihydrogen be increased in this process?



11) 3 in moles per litre in a sample, which has a density, 1.41 g -1, and the mass percent of nitric acid in it being 69%.

12) Use the periodic table to answer the following questions:

(i) Identify an element with 5 electrons in the outer sub shell.

(ii) Identify an element that would tend to lose 2 electrons.

(iii) Identify an element that would tend to gain 2 electrons.

(iv) ) Identify the group having elements in solid, liquid and gaseous state at room

temperature.

13) 3 reacts with aqueous HCl to give CaCl2 2 according to the reaction,

3(s) +2 HCl 2 (aq) 2 (g) + H2 (l),

3 is required to react completely with 25 ml of 0.75 M HCl?

14) Explain why:

(i) BeH2 molecule has a zero dipole moment although the Be—H bonds are polar.

(ii) H2 2

(iii) NH3 molecule is more polar than NF3.

15) A neon—dioxygen mixture contains 70 2 and 167.5 g neon. If pressure of the mixture of

2 and Ne in the mixture?

16) (I) Express the change in internal energy of a system when:-

(a) No heat is absorbed by the system from the surroundings, but work (w) is done on the

system. What type of wall does the system have?

given to the surroundings. What type of wall does the system have?

system. What type of system would it be?

17) (i) At 473K, equilibrium constant, Kc for decomposition of PCl5, is 8.3 x 10-3,if decomposition is

depicted as:

PCl5(g) PCl3(g) + Cl2(g) r—1

(a) Write an expression for Kc for the reaction

(b) What is the value of Kc for the reverse reaction at the same temperature.

c–3. At a given time, the composition of

–4 M. in which direction the reaction will proceed?

18) 2 and CH4 -

stronger intermolecular forces and why?

-



(iii) why vegetables are cooked with difficulty at a hill station ?

19) (A) 2 (g), N2 2 4 (g) are -110, -393, 81,

and 9.7 kj mol-1rH for the reaction:

N2 4 N2 2 (g)

(B) Predict in which of the following, entropy increases/decreases:

(i) A liquid crystallizes into a solid.

20) Balance the following redox reactions by ion-electron method:

4—

(aq) + I—(aq) 2(s) + I2(s) (basic medium)

21)

removing temporary hardness of water .

22) (a) Given the standard electrode potentials, K+ -2.93 V, Hg2+ +

Mg2+ -2.37 V, Cr3+ -0.74 V.Arrange these metals in increasing order of their

reducing power.

(b) Find oxidation no. of the underlined elements in each of the following species:

(i) K2Mn 4 (ii) NaBH4.

(c) Can we use KCl as electrolyte in the salt bridge of the cell:

Cu(s) l Cu2+ +(aq) l Ag (s).

Depict the galvanic cell in which the reaction:

Zn(s) + 2 Ag+ (aq) 2+ (aq) + 2Ag(s), takes place, further show-

(i) Which of the electrode is negatively charged?

(iii) Individual reactions at each electrode.

23) Different types of electromagnetic waves are playing very important role in our day to day life.

Use of X-rays and ultrasound waves is well known in medical field.

emitting and catching radiation. No doubt all these have proved very helpful but there are

strong views that these radiations are harmful if we are exposed to them for a long time.

After reading the above paragraph,answer the following questions:

i. what values are expressed in the above para.

ii. why is it advised not to keep your cellphone in the breast pocket of your shirt.

iii. why a person should go for minimum X-ray.

iv. give one important application of ultrasound waves in medical fields.



24.(a) n - 2.18 x 10—18 )/n2

wavelength of light in cm that can be used to cause this transition?

(II) What is the lowest value of n that allows g orbitals to exist?

(III) a. How many sub-

b. How many electrons will be present in the sub-shells having ms value of –

0 for a metal is 7.0 x 1014s-1.Calculate the kinetic energy of an electron emitted w 15 s-1 -34

esent in 3p orbital. Which electrons will experience more effective nuclear charge? (c)

-particles. If the thin foil of light atoms like aluminium etc. is used, what difference would be observed from the above results?

25) 2 2+

2—

2

2—(peroxide).(b) Compare the relative stability of these species and indicate their magnetic properties also.

(i)Arrange the following in increasing order of their size : (a) Na+ (b) Mg2+ 2- (d) F-

(ii) What are the atomic numbers of elements whose outermost electros are represented by

(a) 2p4 (b) 3p5 (c) 4s1

2 3p3 2 3d1 1

26 (a) what do you mean by pH? a sample of soft drink is

3.8×103 M. What is its pH ?

(b) Describe the effect of:

(i) addition of H2

(ii) addition of CH3

(iv) removal of CH3 e equilibrium of the reaction,

2 H2 (g) (g) 3 (g)

(a)Define Buffer solution. Give example

(b) What is the effect of change in temperature on ‘Kw

Calcula

is 2.0 × 10-15.





QNo

Value Points Point wise mark

mark

1 -axis as internuclear axis,lateral overlapping between the two 2py

-bond.

½+1/2 1

2

from atomic weight to atomic number.

1 1

3 E.C.of 4 2 2s2 e22 *1s2 2 *2s2

- 2 does not exist.

½+1/2 1

4 1 1

5 the production, storage and transportation of energy in the form of liquid or

gaseous H2.

1 1

6 (i)Due to small size of F, the e- -e- repulsions in the 2p-subshell are

comparatively large and hence the incoming e- is not accepted with the

same ease as is the case with larger Cl-atom.

(ii)E.C. of 7 2 2s2 2p3 in which 2p-orbitals are exactly half-filled is more

stable than the E.C. of 8 2 2s2 2p4 in which 2p-orbitals are neither half-

filled or completely filled.

1+1 2

7 P1 1 1 2 2

According to combined gas law,

P1 V1 1 2 V2 2

P2 P1 V1 2 1 V2

P2 676.6 mm Hg

½

½

1

1

8 Aim : C(s) + 2 H2 (g) 2 (g) CH3 (l) f

Eqn. (ii) + 2 X Eqn. (iii) - Eqn. (i) gives the required Eqn. with

- 393 + 2 X (-286) – (- -1 - -1

(i) as the enthalpy

change per mole (or per unit amount)of a substance, when it

½ +

½ + 1

1+1

2

2



undergoes combustion and all the reactants and products being

in their standard states at the specified temperature.

(ii) It is the enthalpy change on breaking one mole of bonds

completely to obtain atoms in the gas phase.

9 (I) the equilibrium reaction is : N2 (g) + 3 H2 (g) 3(g)

32

2 23

-2 2 -2 -2 3

2

(II) Kp c

½+1/2

+1/2

1/2

2

10

C(s) + H2 (g) 1270 K,Ni (g) + H2 (g)

the production of dihydrogen, obtained from coal gasification, can be

increased by reacting (g) of syngas with steam in presence of iron

chromate as catalyst at 673 K.

(g) + H2 (g) 4,673 K 2(g) + H2 (g)

1 + 1 2

11 3 3

by mass.

3 mol-1

3-1

3-1

3

½

½

1

1

3

12 (i) halogens, eg. F, Cl, Brth Gr. (Halogen)

1 X 3 3

13

3 reacting completely with 0.6844 g of HCl

3(s) +2 HCl 2 (aq) 2 (g) + H2 (l)

3

3

0.938 g

½

1

½

1

3



14 (i) BeH2 molecule is linear (H-Be-H ) so that the two Be-H bond moments are

equal and opposite and hence cancel out.

(ii) Due to H – bonding in H2

(iii) In NH3 all the bond dipoles are in same direction as that of lone pair

while in NF3 bond dipoles are opposite to that of lone pair.

1 X 3 3

15 n -1Ne

-1

x Ne -

Pgas total X xgas,

P Ne –

½+1/2

½+1/2

½+1/2

3

16 ad, wall is adiabatic

- q, thermally conducting walls

– w, closed system

1 X 3 3

17 (i) (a) Kc 3 2 5

-

3 X 10-4 M,

½

1

½

½+1/2

3

18 2 c

(ii) At this temp. volume of gas becomes zero

(iii) B.P. decreases because of lower atm .pressure

1 X 3 3

19 f fH (products ) - fH (reactants )

fH (N2 f 2 – fH(N2 4 f

- – -

(B) (i) entropy decreases (ii) entropy increases

½

½

1

½+1/2

20 4—

(aq) + 6I—(aq)+ 4 H2 (l) 2(s) + 3I2(s)

- 1+1+1

for

steps

3

21

whereas permanent hardness is due to chlorides and sulphates of the same

Clark’s method: In this method calculated amount of lime is added to hard

water. It precipitates out calcium carbonate and magnesium hydroxide

which can be filtered off.

3)2 2 3 2H2

1+1+1

3

22 (a) Ag+/Ag < Hg2+/Hg < Cr3+/Cr < Mg2+/Mg < K+/K 1

½+1/2 3



(c) KCl cannot be used as electrolyte in the salt bridge because Cl- ions will

combine with Ag+ ions to form white precipitate of AgCl.

Zn(s) l Zn2+ +(aq) l Ag (s)

(i) zinc electrode (ii) the ions

(iii) Zn(s) Zn2+ (aq) + 2e-, Ag+(aq) + e- Ag (s)

1

1

½+1/2

+1

3

23 (i) the appliances involving electromagnetic radiation of any kind should be

used as little as possible as these radiations are generally harmful in the

living system.

(ii) It is believed that radio waves of cell phone could interact with our heart

this problem is more serious for people using cardiac pacemaker hence it is

advised not to keep cell phone in the breast pocket of shirt.

(iii) X-ray is a type of hjgh energy radiation this can be destructive to all living

cells and can cause DNA damage and mutations.

(iv) Ultra sound waves are high frequency sound waves they are used to

treat pain conditions and to promote tissue healing in physiotherapy.

1X4 4

24 -19

3.65 X 10-5 cm

(a) – -19

(b) Electrons present in 3 p-

effective nuclear charge due to its smaller size.

(c) -particles will deflected more in heavy atoms like gold, platinum

etc. and less deflected in light atoms like Al etc.

1+1

1+1+1

2

1

2

5

25

2 2+

2-

22-

2+

2 2-,

22-

Magnetic properties –Paramgnetic- 2+, 2 2

- ,

22-

i) Mg2+< Na+ < F - 2-

ii)a) 8 b) 15 c)19

½

1/2X4

½

1/2X4

1/2X4

1/2X3

1/2X3

5



26 a)It is the negative logarithm of hydronium ion concentration

Solution

– –

– –

– {(0.58) + (– – { –

and it can be inferred that it is acidic.

of acid or base. Eg. NH4Cl +NH4

b)Increases with increase in temperature

c) Solution

–, –-

K -15 2+ - 2

2

As K

0.10

Hence,2 -13 2+

1+2

1/2X4

5

***************************************************************










each..



words each.


1.

2. Identify the species oxidised and reduced in the following redox reaction.

H2 2

3. What is the pH of our blood? Why does it remain constant inspite the variety of food and spices

we eat?

4. Assign oxidation number to P in (i) NaH2 4 (ii) H4P2 7

5. What is common ion effect?

6. Calculate the mass of an atom of carbon -12 in grams. Express the result up to three significant

figures.

7. Explain why BeH2 molecule has a zero dipole moment although the Be–H bonds are polar.

8.

the reaction occur spontaneously?

b) For the reaction, 2Cl (g) Cl2

9. What do you understand by isoelectronic species? Name a species that will be isoelectronic

with each of the following:

(i) F– (ii) Ar

10. a) Draw the structure of hydrogen peroxide.

b) Hydrogen peroxide is used as a bleaching agent. Why?



Among NH3, H2

bonding and why?

11. Define :

(i) Molarity (ii) Empirical formula (iii) Atomic mass

12. 3.0 g of H2 2 to form H2

(i) Which is the limiting reagent?

(ii) Calculate the maximum amount of H2

(iii) Calculate the amount of the reactant left unreacted.

13. An electron has a speed of 500 m/s with uncertainty of 0.02%. What is the uncertainty in

locating its position?

14. Account for the following:

(i) Electron gain enthalpy of fluorine is less than that of chlorine.

(ii) First ionization enthalpy of boron is less than that of beryllium.

15. 32- ion.

(i) NH3 (ii) H2

16. What will be the pressure exerted by a mixture of 3.2 g of methane and 4.4 g of carbon dioxide

contained in a 9 dm3 flask at 270C ?

17. Explain the following terms:

a) Enthalpy of formation

c) Free energy

18. (i) Write the general outer electronic configuration of d-block elements. (ii) Among the

elements of the third period-

Pick out the element:

a) With the highest ionization enthalpy

b) With the largest atomic radius

on-metal

19. a) For the reaction: 2A(g) + 2B2(g) 2AB2(g), the equilibrium

constantKp at 270C is 4.0 What is the value of Kp for

(i) 2AB2 ( g) 2 A (g) + 2B2 (g)



(ii) A (g) + B2(g) AB2(g)

c for the reaction: 2A B + C is 2 x 10-3 . At a

given time, the concentration of reaction mixtu

3 x 10-4 M. In which direction will the reaction proceed?

20. What is meant by hybridisation of atomic orbital? Give the shapes of sp, sp2, sp3 and sp3d

hybrid orbital.

21. What causes the temporary and permanent hardness of water? Discuss the method of

softening of hard water by synthetic ion exchange resins.

22. Balance the following chemical equations by oxidation number method or ion-exchange

method:

4–(aq) + Br–

2 3– (aq) (in basic medium)

(ii) Fe2+(aq) + Cr2 72– 3+ (aq) + Cr3+(aq) (in acidic medium)

a) What you mean by the term 'oxidation number'?

b) Depict the galvanic cell in which reaction

Zn(s) + 2Ag+ 2+ (aq) +2Ag(s) takes place. Further show:

(i) Which of the electrode is negatively charged,

(ii) in the cell, and

(iii) Individual reaction at each electrode.

23.

fifteen

(i) Who will cook vegetables and pulses faster and why?

(ii) What is reason for delay i

(iii)

(iv)

24. a) Differentiate between an orbit and an orbital.

maximum number of electrons having same spin in it?

c) What is the nu

d) How many radial nodes are present in 3p orbitals?

e) What is the



a) Write the electronic configuration of Cr+3ion.

b) What is Pauli's exclusion principle? Why is it called exclusion principle?

c) Explain why exactly half-filled and completely filled orbitals are extra stable?

25. a) Derive the relationship between Cp and Cv.

b) Calculate the standard enthalpy of formation of CH3

from the following data:

(i) CH3 2 (g) 2(g) + 2H2 rH0 -

(ii) 2 (g) 2 cH0 -

(iii) H2 2 (g) H2 fH0 -

ate the law on which it is

based. 0 – 0 – 0

for the reaction, and predict whether the reaction may occur spontaneously.

26. a) What is solubility product of a salt? Find out the relationship between

the solubility and solubility product of CaF2.

b) Predict if the solutions of the following salts are neutral, acidic or basic:

NaCl, KBr, NaCN, NH4 3 2 and KF

(i) Describe the effect of the following on the equilibrium of the reaction:

2H2 CH3

a) addition of H2 b) addition of CH3

moval of CH3

(ii) What is meant by the conjugate acid-base pair? Find the conjugate acid/base for the

following species:

2, CN–4

2–





Q.

1 12 H2 ine is reduced. 1

3 pH of our blood is 7.4. It remains constant because it is a buffer. 1

4 a) +5 b) +5 1

5 It is defined as the suppression of the degree of dissociation of a weak electrolyte by the addition of a strong electrolyte containing a common ion.

1

6 mass of an atom of C- 0-23 g 1+1

7 BeH2 is a linear molecule, the resultant dipole moment of two Be-H bonds get cancelled giving zero dipole moment.

2

8 - -ve

1 ½ + ½

9 - 1+ ½ + ½

10 (a) Correct structure

bleaching action of H2 2 is due to oxidation of colouring matter by nascent oxygen.

since electronegativity of F is the highest, so, magnitude of the +ve charge on hydrogen and -ve charge on F is the highest and hence H-bonding is strongest in H-F.

1 +1

11 (i) no. of moles present per litre of the solution (ii) which gives the simplest whole no. ratio present between the different atoms in a compound (iii) mass of an atom as compared with 1/12 of the mass of C-12 atom

1 + 1+ 1

12 (i) 3 g of H2 req 2

Hydrogen is the limiting reagent.

(iii) 2

1 1 1

13

uncertainty in -4 m

1 1 1

14 (a) Due to smaller size of F electron –electron repulsions are very strong (b) ) in Be electron is to be removed from fully filled 2s orbital (c ) small size,absence of vacant d-orbitals

1 1 1

15 (a) Correct structure (b) ) NH3- pyramidal,H2 -bent or angular

1 1 +1



16 moles of CH4 44

2 24 -3 m3)

4 Pa

1 1 1

17 (a) No. of moles present per litre of the solute (b) which tells about the simplest whole no. ratio of different atoms present in a compound (c ) mass of an atom as compared with 1/12of the mass of C-12 atom

1 1 1

18 (i) ns0-2(n-1)d1-10 1

219 a) (i) 0.25 (ii) 2

b) in reverse direction1+1 1

20 f slightly different energies to form equal no. of new set of orbitals of same energy and shape is called hybridization. sp is linear, sp2 trigonal planar, sp3 tetrahedral and sp3d trigonal bipyramidal.

1 ½ x 4

21carbonates. Permanent hardness is due to the presence of soluble salts of magnesium and calcium in the form of chlorides and sulphates in water.

anionand is called demineralised water.

2 + 1

22 4–(aq) + Br–(aq) + H2 2 3

– –(aq) b) 6Fe2+(aq) + Cr2 7

2–(aq) + 14H+ 3+(aq) + 2Cr 3+(aq) + 7H2

the charge which an atom appears to have when present in the combined state. b) Zn (s) l Zn+2 (aq) ll Ag+(aq) l Ag(s) (i) Zinc electrode is negatively charged.

from Zn to Ag electrode. (iii) Zn(s) Zn+2 (aq) + 2 e and Ag+(aq) + e Ag(s)

1½ 1½ or 1 ½ ½ 1

23heat of steam is also used in cooking.

e is less at hill station due to which water boils below

ic method to save time, money and energy.

1 1 1 1

24 a) An orbit is a well defined circular path around the nucleus in which the electron revolves whereas an orbital is a three-dimensional region around the nucleus where there is maximum probability of finding the electron. b) 7 electrons c) 9 orbitals (1 in 3s, 3 in 3p and 5 in 3d)

- l - - 1 -2 denotes the probabilityof finding electron at a point.

1 1 1 1 1



a) 1s2 2s2 2p6 3s2 3p6 4s03d3 03d3 b) No two electrons in an atom can have the same set of four quantum

exclusion principle because if one electron has a particular set of four quantum numbers then others are excluded from having that set. c) (i) symmetry (ii) exchange energy

1 2 2

25 a) correct derivation b) Do eq(ii) + 2 x eq(iii) – eq(i)

-393 + 3 x (-286) – (-726) -

a) At 0 K, there is a perfectly ordered arrangement of the constituent particles of a pure crystaliine solid, so entropy is taken zero.It is based on third law of thermodynamics.

g - -1 0 0

g - 0 0 - 0

2 3

26 s the product of the molar concentrations of its ions in a saturated solution, each concentration raised to the power equal to the number of ions produced on dissociation of one mole of the electrolyte.

+2 - 2 2 3 2 , KF solutions are basic

NaCl, KBr solutions are neutral NH4 3 solutions is acidic.

i) a) Equilibrium will shift in the forward direction b) Equilibrium will shift in the backward direction c) Equilibrium will shift in the backward direction d) Equilibrium will shift in the forward direction ii) An acid-base pair which differ by a proton.

2-

4- and H2

2 + 3

****************************************************





S. No. UnitVSA

1 Marks

SA I

2 Marks

SA II

3 MarksVBQ

LA

5 MarksTotal

1 Some basic concept of chemistry 2(1) 3( 2) 8(3)

2 Structure of atom 1 (1) 4(1) 5 (1) 10(3)

3 Classification of elements 1 ( 1 ) 3(2) 7(3)

4 Chemical bonding 2(1) 3 (2) 8(3)

5 States of matter 1 (1) 3 (2) 7(3)

6 Thermodynamics 2(1) 3(1) 5 (1) 10(3)

7 Equilibrium 1 (2) 3 (1) 5 (1) 10 (4)

8 Redox reaction 2(1) 3(1) 5(2)

9 Hydogen 2(1) 3(1) 5(2)

TOTAL 4(5) 10(5) 36(12) 4(1) 5 (3) 70(26)










each..



words each.


Q.1. Write de-Broglie expression for wavelength of matter wave.

Q 2 Give the IUPAC name and symbol of an element having atomic number 118.

Q.3.Under what conditions of temperature and pressure do real gases tend to show ideal gas

behaviour ?

Q.4.Write the expression for kpfor:-

3(g) 2 2 (g)

Q 5 Write the conjugate acid and base of NH3.

form 250ml of the solution.

OR

nd ionization energy is

higher. Why?

Q 8 For a reaction at 298 K 2 A + B -1 -1

be constant over the temperature range ?



Q 9 Write chemical reactions to show amphoteric nature of water.

H2 4, H2 5, KMn 4 and K2Cr2 7.

I. 52g of He

II. 52u of He.

3 reacts with a3 (s) + 2HCl (aq) 2 (aq) 2 (g) + H2 (l).

3 is required to react completely with 25 ml of 0.75M HCl?

Q 13. Calculate the enthalpy of formation of benzene using following data:-

(l) 0 -

H 0 -

H2 2 (g) H20 -

Q 14. Balance the following ionic equation by ion electron method or oxidation number method in acidic medium - 3

-1 Mg2+ + N2 2

Q 16 . (a) Why chlorine has higher electron gain enthalpy than fluorine ?

(b) Why Nitrogen has higher first ionization potential than oxygen atom?

2 2 is

2.0 X 10 -15

(b)Predict if the solutions of following salts are neutral, acidic or basic. NaCl & KF.

(i) BCl3 (ii) BeCl2 6

2 and 4 g H2 confined in a vessel of volume 1

dm3 at 270 -0.083 bar dm-3 K-1 mol-1).

Q 20 (a) Why are the axial bonds longer as compared to equatorial bonds in PCl5?

Q 21 (a) Write Van der waa

(b) Discuss in brief the significance of van der waa

Q 22 Compare the relative stability of the following species and indicate their magnetic properties.

2+

2-

22- (Peroxide)

Q 23 By studying the spectrum of light coming from some distant star, it becomes possible to

identify the elements present on the star. Answer the following questions:

(i)How does a scientist identify the elements present on the star by studying the spectrum

of light from the star?



(ii) What are the wavelengths of the two characteristic lines in the visible region in the

atomic spectrum of sodium?

(iii) What is the value associated with this ?

Q 24 (a

(i)

(ii)

(iii)

(b) Cr2+, Fe and Cl-1.

( c ) G

OR

(a) Give two limitation of Bohr`s Atomic Model.

(c) A microscope using suitable photons is employed to locate an electron in an atom With in

distance of 0.1 A. what is the uncertainty involved in the measurement of its velocity.

- chatelier ‘s principle

b) What will be the effect of increase in pressure on the following equilibria:-

(1) H2 (g) + I2

(2) N2 (g) + 3H2 3 (g).

(3) N2 4 (g) 2(g)

a) Give an example of acidic buffer.

Cu2+ , H2 3 , —1

c) What will be the pH of 0.002M HCl ?

Q26 (a)What will happen to entropy when

0, Given

—1 mol—

OR

(b) For the reaction

2A(g) + B(g) 2D (g)

UØ - Ø - -1

Calculate GØ for the reaction and predict whether the reactions may occur spontaneously.





A 2. Ununoctium uuo 1 Marks

A 4 Correct Expression+ -

Molarity

A 7 Correct Difference OR

Explanation on the basis of e.c of Na and stable e.c of Na+ ion 2 Mark

- 1/2

------------------------------1/2

-1 -1 mol-1) -----------------------------(1)

---------------------------------------------------- --------1/2

---------------------1/2

A 9 Give any two reactions with an acid and a base i.e. HCl and NH3.

A 10 +6,+6,+7 and +6 resp.

A 11 13 x 6.022x1023 and 13 atoms.

A13. C6H6

H C6H6 - 2356.6 – Kj / Mole 3 Marks

A 14 . Correct Balancing by any one of the method 3 Marks

A 15 Correct structure 1 Mark

2 Mark

A 16 a) Very small size of 2p subshell in flourine and explanation 1.5 Mark

1.5Mark



-15 2+ - 2

-13M 2+1

(b) NaCl- Neutral, KF- Basic

A 18 1 mark each

2

224

2Hn

22 HOH nnT

n

3

VnRTP 3

A 20. (a) less bond angle so more repulsion at axial position

(b) any correct two difference 2+1

A 21 (a) Correct equation 1

ng the molecule of a particular

gas 1

etermine the volume occupied by the gas molecules which depend upon size of

molecule 1

A 22. 22-

2-

2+

2- -------------Diamagnetic

22-

2- -----------Paramagnetic

A 23 (i) Each element has characteristic line spectrum. By comparing the lines present in the

spectrum of light from the star with those of the atomic spectra of elements a scientist

identifies the he sun, was

detected by studying the spectrum of light from the sun.

emitted by sodium vapour lamps

(iii) use of chemistry in research

A 24 Proper definition and proper electronic configuration

OR



2

b) Correct Definition 1

c) ½ mark for correct formula, 1 mark for calculation and ½ marks for answer.

A 25 a) Exact definition + exact explanation --------------------------- 1+1

b) i) No effect

ii) gets shifted to the right

iii) Gets shifted to the left (1+1+1)

a) CH3 3 --------------------------------------- -(1)

b) lewis acid Cu2+, BF3

lewis basis H2-

c) - + -1

- log (2 x 10-3)

- (-3 +0.3010)

A 26 a) i) Entropy increases (1+1)

ii) Entropy decreases

b 0 -

- ------------------------------------------------ 1/2-1 mol-1 -------------------------------------- 1

- -1mol-1) x (300k)X (log 10) ---------------------- 1/2

- -1 - -1 ------------------------------------ (1)

a) Enthalpy change in a reaction is same weather the reaction takes place in one step or in

several steps. With any example (2)

b) -

– 298 (-44.1x103)

(3)



half-yearly examination class:xi sub:...

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