physics, chemistry mathematics

CodeA

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SAMPLE QUESTION PAPER

Physics, Chemistry&

Mathematics

CBSE Class XII Board Exam 2018

(1)

Physics (Code-A) Sample Question Paper for Class XII

Time : 3 Hours Max. Marks : 70

General Instructions :

(i) All questions are compulsory.

(ii) There is no overall choice. However an internal choice has been provided in one question of 2 marks,

one question of 3 marks and all three questions of 5 marks each. You have to attempt only one of the

choices in such questions.

(iii) Questions 1 to 5 are very short answer type and carry 1 mark each.

(iv) Questions 6 to 10 are short answer type and carry 2 marks each.

(v) Questions 11 to 22 are short answer type and carry 3 marks each.

(vi) Question 23 is a value based question and carries 4 marks.

(vii) Questions 24 to 26 are long answer type and carry 5 marks each.

(viii) Use of calculator is not permitted.

(ix) You may use the following values of physical constants wherever necessary :

c = 3 × 108 ms–1

h = 6.626 × 10–34 Js

e = 1.602 × 10–19 C

0 = 4 × 10–7 T mA–1

9 2 2

0

19 10 Nm C

4

Mass of neutron mn = 1.675 × 10–27 kg

Boltzmann’s constant k = 1.381 × 10–23 JK–1

Avogadro’s number NA = 6.022 × 1023

SAMPLE QUESTION PAPERPhysics (Theory) - Class XII (Code-A)

SECTION-A

Very Short Answer Type Questions :

1. What is the phase difference between voltage across capacitor and voltage across inductor in series LCR

circuit? [1]

2. The intensity of central maximum in the interference pattern of Young's double slit experiment (having slits

of equal width) is I0. If one of the slit is covered then what will the intensity at central point? [1]

3. Write Boolean expression for the following combination of gates. [1]

A

B

Y

(2)

Sample Question Paper for Class XII Physics (Code-A)

4. A biconcave lens made of a transparent material of refractive index 1.25 is immersed in water of refractive

index 1.33. Will the lens behave as a converging or a diverging lens? Give reason. [1]

5. How does the mutual inductance of a pair of coils change when

(a) Distance between the coils is decreased?

(b) Number of turns in the coils is decreased? [1]

SECTION-B

Short Answer Type Questions :

6. What are the advantages of digital data over the analog data? [2]

OR

Name two universal gates. Why they are called universal gates? Hence, draw an arrangement of NAND gates

that works as a OR-gate.

7. The instantaneous current from A.C. source is given by, 5sin(314t) ampere. What are average and RMS values

of current? [2]

8. Outline the principle on which KVL and KCL are based. [2]

9. A variable resistor R is connected across a cell of emf and internal resistance r (Figure). Draw a plot showing

the variation of

I

, r

R

I

(a) Terminal voltage V as function of I.

(b) The current I, as function of R. [2]

10. Using Rutherford model of the atom, derive an expression for the total energy of the electron in hydrogen

atom. [2]

SECTION-C

11. Explain the working of p-n junction diode. [3]

OR

Describe, the active mode, cut-off mode and saturation mode in case of transistor action.

12. What is space wave propagation? Which two communication methods make use of this mode of propagation?

If the sum of the heights of transmitting and receiving antennae in line of sight of communication is h, show

that the range is maximum, when two antennae have a height 2

h each. [3]

(3)


13. Draw a neat and labelled ray diagram of a compound microscope. Derive an expression of its magnifying

power. [3]

14. The given figure shows the experimental setup of a metre bridge. The null point is found to be 60 cm away

from end A with resistances X and Y as shown in figure. When a resistance of 15 is connected in series

with Y, the null point is found to shift by 10 cm towards the end A of the wire. Find the position of null point

if a resistance of 30 were connected in parallel with Y. [3]

K

C

YX

B

A

D

15. (a) Write down four properties of electromagnetic waves. [3]

(b) Identify the part of electromagnetic spectrum which is (i) suitable for radar system (ii) produced in nuclear

reaction (iii) Produced by bombarding a metal by high speed electron.

16. Find the magnetic field intensity at the centre of loop if the resistance of upper part is double that of lower

part. [3]

R

II

17. A voltage V = V0sint is applied to a series LCR circuit. Derive the expression for the average power dissipated

over a cycle. [3]

18. In the circuit shown in figure, when the input voltage of the base resistance is 10 V, VBE

is zero and VCE

is

also zero. Find the values of IB, IC and . [3]

VI

RB

400 k

RC

3 k

10 V

(4)


19. Consider a metal exposed to light of wavelength 600 nm. The maximum energy of the electron doubles when

light of wavelength 400 nm is used. Find the work function in eV. [3]

20. Why is an AM signal likely to be more noisy than a FM signal upon transmission through a channel? [3]

21. A nuclide 1 is said to be the mirror isobar of nuclide 2 if Z1 = N

2 and Z

2 = N

1. (a) What nuclide is a mirror

isobar of 2311Na? (b) Which one out of the two mirror isobars have greater binding energy and why? [3]

22. Explain, why the reactance offered by an inductor increases with increasing frequency of an alternating

voltage? [3]

SECTION-D

23. One morning an old man walked barefoot to replace the fuse wire in kitkat fitted with power supply mains

for his house. Suddenly he screamed and collapsed on the floor. His wife cried loudly for help. His neighbour’s

son Anil heard the cries and rushed to place with shoes on. He took a wooden baton and used it to switch

off main supply.

Answer the following questions : [4]

(a) What is the frequency and voltage of power main supply in India?

(b) Can a transformer be used to step up DC voltage?

(c) On which principle transformer works?

SECTION-E

Long Answer Type Questions :

24. (a) Figure shows a network of five capacitors connected to a 100 V supply. Calculate the total charge and

energy stored in the network.

3 F

3 F 1 F 2 F

2 F

100 V

(b) Obtain an expression for the capacitance of a parallel plate capacitor filled with air as medium. [5]

OR

(a) Use Gauss’s law to obtain an expression for electric field due to an infinitely long straight uniformly charged

wire.

(5)


(b) Electric field in the figure given below is directed along +ve (positive) X-axis and is given by

5 2x

E Ax B , where E is in N/C and x is in metre, A and B are constant with dimensions.

10 cmZ

XE

x

Y

M N

Taking A = 10 NC–1m–1 and B = 5 NC–1m–1, calculate

(i) Electric flux through the cube.

(ii) Net charge enclosed within the cube.

25. In Young’s double slit experiment, describe briefly how bright and dark fringes are obtained on the screen kept

in front of a double slit. Hence obtain the expression for the fringe width. [5]

OR

(a) Find the expression of magnetic field intensity due to a straight conductor at point P.

PL

I

d

(b) Using the result of part (a), find the expression of magnetic field due to infinite and semi-infinite conductor

carrying same current at point P.

26. A device ‘X’ is connected to an AC source V = V0sint. The variation of voltage, current and power in one

cycle is shown in the following graph :

Y

t

AB

C

0 2

(6)


(a) Identify the device ‘X’.

(b) Which of the curves A, B and C represent the voltage, current and the power consumed in the circuit?

Justify your answer.

(c) How does its impedance vary with frequency of the AC source? Show graphically.

(d) Obtain an expression for the current in the circuit and its phase relation with AC voltage. [5]

OR

Draw a labelled diagram of an AC generator. Obtain the expression for the emf induced in the rotating coil

of N turns each of cross-sectional area A, in the presence of a magnetic field B

�

.

� � �

(7)

Chemistry (Code-A) Sample Question Paper for Class XII




(ii) The question paper consists of four sections A, B, C and D.

Section A contains 5 questions of 1 mark each.

Section B contains 5 questions of 2 marks each.

Section C has 12 questions of 3 marks each and one value based question of 4 marks, whereas Section D

contains 3 questions of 5 marks each.

(iii) There is no overall choice. However, an internal choice has been provided in one question of 2 marks,

one question of 3 marks and all three questions of 5 marks each. A student has to attempt only one of the

alternatives in such questions.

(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.

SAMPLE QUESTION PAPERChemistry (Theory) - Class XII (Code-A)

SECTION-A


1. Define the term : Primitive unit cells. [1]

2. What type of colloid is formed when a gas is dispersed in a liquid? Give an example. [1]

3. Write the IUPAC name of the given compound? [1]

CH – CH – OH2 2

4. Using IUPAC norms, write the formula for the following. [1]

Potassium trioxalatoaluminate(III)

5. Which would undergo SN1 reaction faster in the following pair? [1]

CH – C – CH3 3

CH – CH – Br and3 2

CH3

Br

SECTION-B


6. How many electrons flow through a metallic wire if a current of 0.5 A is passed for 2 hours?

(Given : 1 F = 96, 500 C mol–1) [2]

7. Arrange the following in increasing order of their basic strength. [2]

(i) C6H5 – NH

2, C

6H5 – CH

2 – NH

2, C

6H5 – NH – CH

3

(ii)

NH2

NO2

NH2

CH3

NH2

, ,

(8)

Sample Question Paper for Class XII Chemistry (Code-A)

8. When a coordination compound CoCl3.6NH

3 is mixed with excess of AgNO

3, 3 moles of AgCl are precipitated

per mole of the compound. Write

(i) Structural formula of the complex [1]

(ii) IUPAC name of the complex [1]

9. For a reaction : h

2 2H Cl 2HCl

Rate = k

(i) Write the order of this reaction. [1]

(ii) Write the unit of k. [1]

10. Write the structures of the following molecules:

(i) H2SO

3[1]

(ii) XeOF4

[1]

OR

Write the structure of the following molecules.

(i) H3PO

4

(ii) XeO3

SECTION-C


11. An element crystallizes in a bcc lattice with cell edge of 500 pm. The density of the element is 7.5 g cm–3. How

many atoms are present in 300 g of the elements? [3]

12. Give reasons for the following : [3]

(a) Red phosphorus is less reactive than white phosphorus

(b) Electron gain enthalpies of halogens are largely negative

(c) N2O5 is more acidic than N

2O3.

13. 30 g of urea (M = 60 g mol–1) is dissolved in 846 g of water. Calculate the vapour pressure of water for this

solution if vapour pressure of pure water at 298 K is 23.8 mm Hg. [3]

14. Write differences between ideal solutions and non-ideal solutions. [3]

15. A first order reaction takes 20 minutes for 25% decomposition. Calculate the time when 75% of the reaction

will be completed. (Given : log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021) [3]

16. Define the following : [3]

(a) Anionic detergents

(b) Limited spectrum antibiotics

17. Write the structures of the monomers used for getting the following polymer: [3]

(a) Nylon-6,6

(b) Melamine-Formaldehyde polymer

(c) Buna-S

OR

Write name of monomer used for getting the following polymer.

(a) Buna-N

(b) Natural rubber

(c) Teflon

(9)

Chemistry (Code-A) Sample Question Paper for Class XII

18. Write the structures of compounds A, B and C in the following reactions : [3]

(a) 3 32NH / CHCl alc.KOHBr /KOH(aq)3CH —COOH A B C

(b) 32 CH COCl/pyridineNaNO /Cu Fe/HCl–

6 5 2 4C H N BF A B C

19. Write the structure of the major product in each of the following reactions. [3]

(i) CH – CH = C – CH + HBr3 3

CH3

(ii) CH – CH – CH – CH – CH + KOH3 2 2 3

Br

ethanol/heat

(iii) + CH Cl3

anhyd. AlCl3

CH3

20. (i) Name the method of refining of nickel. [1]

(ii) What is the role of cryolite in the extraction of aluminium? [1]

(iii) What is the role of limestone in the extraction of iron from its oxides? [1]

21. Write the final product(s) in each of the following reactions : [3]

(a) CH3

C O CH3+HI

CH3

CH3

(b) CH3

OH

CH2

CH CH3

Cu/573 K

(c) 3(i) CHCl aq.NaOH

6 5 (ii) HC H OH

22. (i) Write the product obtained when glucose reacts with H2N – OH. [1]

(ii) Amino acids show amphoteric behaviour. Why? [1]

(iii) Why cannot vitamin C be stored in our body? [1]

23. Due to hectic and busy schedule, Mr. Singh started taking junk food in the lunch break and slowly became

habitual of eating food irregularly to excel in his field. One day during meeting he felt severe chest pain and

fell down. Mr. Khanna, a close friend of Mr. Singh took him to doctor immediately. The doctor diagnosed that

Mr. Singh was suffering from acidity and prescribed some medicines. Mr. Khanna advised him to eat home

made food and change his lifestyle by doing yoga meditation and some physical exercise. Mr. Singh followed

his friend’s advice and after few days he started feeling better.

After reading the above passage, answer the following: [4]

(i) What are the values (at least two) displayed by Mr. Khanna?

(ii) What are antacids? Give one example.

(iii) Would it be advisable to take antacids for a long period of time? Give reasons.

(10)

Sample Question Paper for Class XII Chemistry (Code-A)

SECTION-D

Long Answer Type Questions :

24. (i) Account for the following :

(a) Zr and Hf have almost similar atomic radii. [1]

(b) Transition metals show variable oxidation states. [2]

(ii) Complete the following equations :

(a) 2KMnO4

513 K [1]

(b) 2Na2CrO

4 + 2H+ [1]

OR

(i) Following are the transition metal ions of 3d series :

Ti4+, V2+, Mn3+, Cr3+

Answer the following questions :

(a) Which ion is most stable in aqueous solution and why? [1]

(b) Which ion is a strong oxidising reagent and why? [1]

(c) Which ion is colourless and why? [1]

(ii) Write one similarity and one difference between the chemistry of lanthanoids and actinoids. [2]

25. Calculate emf and G for the following cell : [5]

Mg(s) | Mg2+ (0.001 M) || Cu2+ (0.0001 M) | Cu(s)

Given : 2 2

o o

(Mg /Mg) (Cu /Cu)E 2.37 V, E 0.34 V

OR

The conductivity of 0.20 mol L–1 solution of XCl is 2.48 × 10–2 S cm–1. Calculate its molar conductivity and degree

of dissociation (). [Given °(X+) = 73.5 S cm2 mol–1 and ° (Cl–) = 76.5 S cm2 mol–1] [5]

26. (a) Write the structure of A and B in the following reactions : [5]

(i) 2 4 2H /Pd BaSO H N OH

3CH COCl A B

(ii) 52

3

PCl1. CO

3 2.H OCH MgBr A B

(b) Distinguish between

(i) C6H5 – COCH

3 and C

6H5 – CHO

(ii) CH3CH

2COOH and HCOOH

(c) Arrange the following in the increasing order of their boiling points :

CH3COCH

3, CH

3COOH, CH

3CH

2OH

OR

(a) Write the chemical reaction involved in Etard reaction. [1]

(b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction. [1]

C6H5COCH

3, CH

3 – CHO, HCHO

(c) Why pKa of Cl – CH

2COOH is lower than that of CH

3COOH? [1]

(d) Write the product in the following reaction : [1]

2

3 2 2

2

1. (i Bu) AIHCH CH CH CH– CH CN

2.H O

(e) A and B are carbonyl compounds and two functional isomers of compound C3H6O. On heating with NaOH

and I2 isomer A forms yellow precipitate of iodoform whereas isomer B does not form any precipitate. Write

the formulae of A and B. [1]

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(11)

Mathematics (Code-A) Sample Question Paper for Class XII




(ii) The question paper consist of 29 questions divided into three sections A, B, C and D. Section A comprises

of 4 questions of one mark each, section B comprises of 8 questions of two marks each, section C

comprises of 11 questions of four marks each and section D comprises of 6 questions of six marks each.

(iii) All questions in Section A are to be answered in one word, one sentence or as per the exact requirement of

the question.

(iv) There will be no overall choice. However, internal choice has been provided in three questions of 4 marks

each and two questions of 6 marks each. You have to attempt only one of the alternatives in all such

questions.

(v) Use of calculator is not permitted. You may ask for logarithmic tables, if required.

SAMPLE QUESTION PAPERMathematics - Class XII (Code-A)

SECTION-A


1. If ˆ ˆ ˆ4a i j k �

and ˆ ˆ ˆ2 2 ,b i j k �

then find a unit vector parallel to the vector a b�

�

. [1]

2. Write the principal value of tan–1 13 cot 3 .

[1]

3. If A is a square matrix such that A2 = A, then write the value of 7A –(I + A)3, where I is an identity matrix.[1]

4. Find : 2 2

sin cos

sin cos

x xdx

x x

∫ [1]

SECTION-B


5. If 3 7 8 7

,2 4 6 4

x

find the value of x. [2]

6. The money to be spend for the welfare of the employees of a firm is proportional to the rate of change of its

total revenue (marginal revenue). If the total revenue (in rupees) received from the sale of x units of a product

is given by R(x) = 3x2 + 36x + 5, find the marginal revenue, when x = 5, and write which value does the

equations indicate. [2]

7. Find a vector of magnitude 171 which is perpendicular to both of the vectors ˆ ˆ ˆ2 3a i j k �

and

ˆ ˆ ˆ3 2b i j k �

. [2]

(12)

Sample Question Paper for Class XII Mathematics (Code-A)

8. If f(x) = 0

sin ,

x

t t dt∫ then write the value of f (x). [2]

9. Find the sum of the order and the degree of the following differential equation: [2]

y = x

3

dy

dx

⎛ ⎞⎜ ⎟⎝ ⎠ +

2

2

d y

dx

10. If matrix A = 1 1

1 1

⎡ ⎤⎢ ⎥⎣ ⎦

and A2 = kA, then write the value of k. [2]

11. Find the solution of the following differential equation: [2]

2 21 1 0x y dx y x dy

12. Evaluate :

4

2

21

xdx

x ∫ [2]

SECTION-C

Long Answer-I Type Questions :

13. A man takes a step forward with probability 0.4 and backward with probability 0.6. Find the probability that

at the end of 5 steps, he is one step away from the starting point. [4]

OR

Suppose a girl throws a die. If she gets a 1 or 2, she tosses a coin three times and notes the number of

‘tails’. If she gets 3, 4, 5 or 6, she tosses a coin once and notes whether a ‘head’ or ‘tail’ is obtained. If she

obtained exactly one ‘tail’, what is the probability that she threw 3, 4, 5 or 6 with the die?

14. Find the value of , if four points with position vectors ˆ ˆ ˆ3 6 9 ,i j k ˆ ˆ ˆ2 3 ,i j k ˆ ˆ ˆ2 3i j k and ˆ ˆ ˆ4 6 ,i j k

are coplanar. [4]

15. Show that the lines [4]

ˆ ˆ ˆ ˆ ˆ ˆ3 2 4 2 2r i j k i j k �

ˆ ˆ ˆ ˆ ˆ5 2 (3 2 6 )r i j i j k �

are intersecting. Hence find their point of intersection.

OR

Find the vector equation of the plane through the points (2, 1, –1) and (–1, 3, 4) and perpendicular to the plane

x – 2y + 4z = 10.

16. Evaluate : 5( 3)

dx

x x ∫ [4]

(13)

Mathematics (Code-A) Sample Question Paper for Class XII

17. Show that: 11 3 4 7

tan sin2 4 3

⎛ ⎞ ⎜ ⎟⎝ ⎠ [4]

18. Find the particular solution of the differential equation 1 ,dy

x y xydx

given that y = 0 when x = 1. [4]

19. Evaluate : 22

2

0

cos

1 3sin

xdx

x

∫ [4]

20. Differentiate the following with respect to x :

1

1 2 3sin

1 (36)

x x

x

⎛ ⎞⎜ ⎟⎝ ⎠ [4]

21. Find the value of k, for which f(x) =

1 1, if 1 0

2 1 , if 0 1

1

kx kxx

x

xx

x

⎧ ⎪⎪⎨

⎪ ⎪⎩

is continuous at x = 0. [4]

OR

If x = a cos3and y = a sin3, then find the value of 2

2

d y

dx at .

6

22. Solve the differential equation (tan–1x – y)dx = (1 + x2)dy. [4]

23. Consider f : R+ [4, ) given by f(x) = x2 + 4. Show that f is invertible with the inverse f–1 of f given by

f–1(y) = 4y , where R+ is the set of all non-negative real numbers. [4]

SECTION-D

Long Answer-II Type Questions :

24. A manufacturer considers that men and women workers are equally efficient and so he pays them at the same

rate. He has 30 workers (male and female) and 17 units of capital, which he uses to produce two types of

goods A and B. To produce one unit of A, 2 workers and 3 units of capital are required while 3 workers and

1 unit of capital is required to produce one unit of B. If A and B are priced at ` 100 and ` 120 per unit

respectively, how should he use his resources to maximise the total revenue? Form the above as an LPP

and solve graphically. Do you agree with this view of the manufacturer that men and women workers are equally

efficient and so should be paid at the same rate? [6]

25. Using properties of determinants, prove that

2

2 3

2

( )

( ) 2 ( )

( )

x y zx zy

zx z y xy xyz x y z

zy xy z x

[6]

(14)

Sample Question Paper for Class XII Mathematics (Code-A)

26. Find the equation of the plane passing through the line of intersection of the planes ˆ ˆ3 6 0r i j �

and

ˆ ˆ ˆ3 4 0,r i j k �

whose perpendicular distance from origin is unity. [6]

OR

Find the vector equation of the line passing through the point (1, 2, 3) and parallel to the planes

ˆ ˆ ˆ2 5r i j k �

and ˆ ˆ ˆ3 6r i j k �

.

27. An urn contains 5 red and 2 black balls. Two balls are randomly drawn, without replacement. Let X represent

the number of black balls drawn. What are the possible values of X? Is X a random variable? If yes, find the

mean and variance of X. [6]

28. Consider f : R – 4 4

3 3R given by f(x) =

4 3

3 4

x

x

. Show that f is bijective. Find the inverse of f and

hence f–1(0) and x such that f–1(x) = 2. [6]

OR

Let A = Q × Q and let * be a binary operation on A defined by (a, b) * (c, d) = (ac, b + ad) for (a, b),

(c, d) A. Determine, whether * is commutative and associative. Then, with respect to * on A

(i) Find the identity element in A.

(ii) Find the invertible elements of A.

29. Using integration, find the area of the region bounded by the triangle whose vertices are (–1, 2), (1, 5) and

(3, 4) [6]

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