CBSE Notes

BRAIN BOOSTERS

by chemistry on April 24, 2010

1. For a solution of 3.795 g sulphur in 100 g CS₂,the boiling point was 319.81 K. For pure CS₂,

the boiling point is 319.45 K and the enthalpy of vaporization is 351.87 Jg^-1. What is the molar

mass and formula’ofsu1jhur in CS₂?

2. The solubility products of Pbl₂ is .7.50 x 1O-⁹at15°C and 1.58 x 10^-8 at 25°C. Calculate solubility

in g/L at 75°C?

3. Iron Crystallizes indifferent modifications. At about 910°C the body cent red cubic form undergoes transition to the face centered cubic y form. Assuming that ‘the distance between the nearest neighbours is same in the two forms at transition temperature, calculate the ratio of the density of iron to that of a iron at that temperature.

4. The wavelength of light evolved associated with an electron Jump from the 5th orbit of Bohr hydrogen atom to the 3rd orbit is 1.28 x10⁴ A⁰. What will be the wavelength of light emitted when the same electron 3rd orbit jumps to the 2nd orbital?

5. Convert using

with aldol condensation as key step.

6. In solid ammonia, each NH₃ molecule has six other NH₃ molecules as nearest neighbours.ΔH of sublimation of NH₃’at the melting point is 30.8 kJ/mole, and the estimated H of sublimation in the absence of hydrogen bonding is 14.4 kJ/mol. What is the strength of hydrogen bond in solid ammonia?

7. A 0.1 m solution of NaCIO₃ freezes at -0.3433°C. What would you predict for the boiling point of this aqueous solution at 1 atm pressure? At 0;001 m concentration of this same salt, the electrical interferences between the ions no longer exist, because the ions are, on an average, too far apart from each other Predict the freezing point of this more dilute solution (K_ffor water = 1.86 K kg mol^-1 and K_b for water = 0.513 K kg mol^-1).

8. An aromatic ketone (X) has the M.F. C₁₀H₁₂O₂ on vigorous oxidation, it gives (Y), dibasic acid (C₉H₈O₅) which easily gives an anhydride on heating. The ketone (K) gives (Z) (C₉H₁₀O₃), a monobasic acid on heating with bromine and NaOH. (Z) on decarboxylation with soda lime gives 3-methyl anisole. Determine (X), (Y) and (Z).

9. Bring about following one step transformations:

10. Two isomeric compounds (A) and (B) on analysis give 45.85% C, 8.91 % hydrogen. Further sodium extract of 1.0 g of the compound gives 1.83 g of AgC1 with acidified AgNO₃ solution Chlorination of (A) with Cl₂ and light gave two dichloro derivatives while (B) gave three different dichloro compounds. What are (A) and (B) and also give the structural formulae of the dichloride’s obtained, from each.

SOLUTIONS

3. For γ form there are 4 atoms per unit cell and edge length

For α form there are 2 atoms per unit cell and edge length

Density of form

Dividing 1 by 2, we get 1.089 1.09 the ratio of their densities.

6. Total strength of all hydrogen bonds

= 30.8— 14.4 = 16.4 kJ/mol.

There are 6 nearest neighbours, but each hydrogen bond involves 2 ammonia molecules.

Strength of each H-bond in solid NH3

On chlorination in presence of light compound (A) gives two dichloro derivatives while (B) gives

three dichloro derivatives.

A must be iso-propyl chloride:

B is n-propyl chloride:

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AIEEE (25-4-2010) paper

by chemistry on April 23, 2010

1.η and l values of an orbital A are 3 and 2,and of another orbital B are 5 and 0. Then, the energy of

(a) B is more than A (b) A is more than B

.(c)A and B are of same energy (d) none of the above.

2. Email volumes of two gases don’t react together are confined in, separate vessels. Their pressure is 100 mm and 30 mm of Hg, respectively. If the two Vessels are joined together, then what will be the pressure of the resulting mixture? (Temperature remains constant)

(a)400 mm ( b)√400

3. When calomel reacts with NH₄OH, we get

(a) Hg₂0 (b) HgO

4. A salt is formed when a weak acid of dissociation constant 10^-4 and weak base of dissociation constant 1O^-5 are mixed. The pH and degree of hydrolysis of salt solution are

(a) 5, 1% (b) 7,12%

5. The maximum kinetic energy of photoelectrons ejected from a metal is x when it is irradiated with radiation having frequency twice the threshold frequency. 11 frequency of the incident radiation is doubled, the maximum kinetic energy of the photoelectrons would become

(a) x (b) 2x

6. Match the List-I with List-U and select the correct answer using the options given below the lists.

List-I. List-Il

(A) -and -glucose 1. mutarotation

(B) (+) and (—)-glucose 2. enantiomers

(D) a-form ‘. open 4. configurational

chain form ., – n-form isomers

(a) A-2; B-3; C-4;D-1 (b) A-2; B-3; C-1; D-4

7. The major organic’ product formed from the following reaction.

8. The correct increasing order of Para magnetism of

i. MnSO₄-4H₂O ii . FeSO₄•7H₂O:

iii. NiS0₄-6H₂O iv. CuSO₄5H₂O

(a) (i) < (ii) < (iii) < (iv)

(b) (iv) < (iii) < (ii) < (i)

(d) (iii) <(iv) <(i) < (ii)

10. Which of the following configuration is associated with biggest jump between 2^nd and 3^rd IE?

11. Identify the, correct statement.

(a) Plaster of Paris can be obtained by hydration of gypsum

(b) Plaster of Paris is obtained by partial oxidation of gypsum

(d) Gypsum is obtained by heating Plaster of Paris.

12. Salts of A (atomic weight 7), B (atomic weight 27) and C (atomic weight 48) were electrolysed under identical conditions using the same quantity of electricity It was found that when 2.1 g of A was deposited, the weights of and C deposited were 2.7 g and 7.2 g. The valencies if A, B and C are respectively

(a) 3,l and 2 (b)1,3 and 2

13. If NaOH is added to an aqueous solution of Zn2+ ions, a white precipitate appears and on adding excess NaOH, the precipitate dissolves. In this solution zinc exists in the

(a) Cationic part (b) anionic part

14. Sometimes a yellow turbidity appears while passing H2S gas even in the absence of II group

radicals. This is because

(a) sulphur is present in the mixture as impurity

(b) IV group radicals are precipitated as sulphides

(d) III group radicals are precipitated as hydroxides

15. An organic liquid A containing C, H and 0 has a pleasant odour with a b.p. of 78°C. On boiling A. with conc. H2S04 a colourless gas is produced which decolourises bromine water and alkaline KMnO4. One mole of this gas also takes One mole of H2. The organic liquid A is

16. Match the lists I and II and pick the correct matching from the codes given below

17. Nucleophibcity order is correctly represented by

18. The correct statement about the compounds I, II and III.

(a) I and II are identical (b). I and II are diastereomers

19.

20. A greenish yellow gas reacts with an alkali metal hydroxide to form a halite which can be used in fire works and safety matches. The gas an4 halite

respectively- are

21. In nitrogen family, the H – M – H bond angle in the hydrides gradually becomes closer o 90° on

going form N to Sb. This shows that gradually

(a) the basic strength of hydrides increases

(b) almost pure. p-orbital are used for M — H bonds

(d) the bond pairs of electrons become nearer to the central atom.

22. At 373 K, a gaseous reaction A →2B+C’is found to be of first order. Starting with pure A, the total pressure at end of 10 min was 176 mm and after a long. time when A was completely dissociated, it was 270 mm. The pressure of A at the estdo1Ominutes1was’

(a) 94 mm (b) 47 mm

23. 0.44 g of a colourless oxide of nitrogen occupies 24 mL at STP. The compound is

(a) N₂O (b) NO (c) N₂0₂ (d) NO₂

24. If P_o and P_sare the vapour pressures of the solvent and solution respectively, n₁ and n₂ are the mole fractions of of the solvent and solute respectively, then

25.

26.

(a) 150 K (b) 75 K (c) 100 K (d) 200 K

27. A binary solid (A⁺B^-) a zinc blende structure with B^-ions constituting g the lattice and A⁺ions occupying 25% tetrahedral holes. The formula of slid is

(a)AB (b)A₂B (c) AB₂ (d) AB₄

28. Which statement is correct?

(a) BCl₃ and AICl₃ are both Lewis acids and BCl₃ is stronger than AICl₃

(b) BCl₃ and A1Cl₃ are both Lewis acids and AlCl₃ stronger than BCl₃

(d) Both BCl₃and AlCl₃ are not Lewis acids

29. Among the compounds;

1. a):A is 3d and. B is 5s; for both is 5 and thus lower value of n decides lower energy level.

3. (C) : When calomel reacts with NH₄0H, it black due to the formation of a mixture of mercury and mercuric amino chloride.

4. (c) : For a salt of weak add and weak base

8.(b): (5 unpaired electrons)

4 unpaired electrons)

2 unpaired electrons)

(1 unpaired electron)

9.(b):

10. (C) : The jump m ionization energy occurs when valence shell changes during removal of electron.

11. (c) : Gypsum is CaSO₄•H₂O and Plaster of Paris is 2(CaSO₄).H₂0. Therefore gypsum contains a lower percentage of calcium than Plaster of Paris.

12.

13.

17. (c): Lesser the electro negativity of. the donor atom, more is its tendency to give a lone pair of electrons, more is its nucleophilicity. Thus, order of nucleophilicity is

]

18.(d): If we rotate II by 180° in the plane of paper then we get a mirror image of I.

19. (d): Oxidation state of

Colour of salts is a property of partially filled d-orbital. Since Ti has, empty d-subshell and Cu₂Cl₂ involves completely filled d-sub shell these are colourless, salts.

20. (b):

KC1O₃ is used in fire works and safety matches as an oxidizing agent.

21. (b): On moving down the group, e1ectronegetivity decreases, consequently bond paw shifts more-and more away from the central atom. HenceH-M-H. Bond angle decreases and becomes closer to 9O⁰ in SbH₃ which reveals that almost pure p-orbitals are used for M-H bonding..

28. (a) : BCI₃ and AICI₃ both are electron deficient compounds and can accept lone pair to act as Lewis acid. Also BCI₃ involves smaller boron atom and thus, attracts electron pair -more easily.

29. (b): Aromatic amines are less basic than aliphatic amines. Also presence of electron attracting group decreases the basic character of aromatic amines.

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Integer type questions(paper-II)

by physics on April 22, 2010

This section contains questions the answer to each of the question is a single digit integer, ranging from 0 to9. The appropriate bubbles have to be darkened. For example, if the correct answers to question

Numbers

1, 2, 3, 4, 5, 6, 7 and 8 (say ate 1,4, 3, 5, 8, 2, 9 and 6 respectively, then the correct darkening of bubbles will look like as shown.

12. The rod is placed on the edge of a tumbler with water so that half of ball is submerged in water when the system is in equilibrium. Density of ball =2700 kg/m³, radius of ball is 0.5 cm and mass of rod =4.4 gram. Find 2y/x

13. A fixed U-shaped smooth has semi-circular bending between A and as shown in the figure.

A bead of mass 1/2 kg moving with uniform speed√∏ through the wire enters the semicircular bend at A and leaves at B. Find the magnitude of average force exerted by the bead on the part AB of the wire.

14. .A gas is enclosed in a vessel at a constant temperature at a pressure of 2atm and volume 4 litres. Due to a leak in the vessel, after some time the pressure is reduced to 1.5 atm. As a result 5v% of the gas as escaped out. What is the value of v?

15. 2 kg ice at -20°C is mixed with 5 kg water at 20°C. Then what is the final amount of water in

the mixture? Given specific heat of ice =0.5 cal/g°C, specific heat of water = 1 cal/g°C, Latent heat of fusion of ice = 80 cal/g.

16.A particle of mass 5000g is moving horizontally with a constant velocity 1m/s towards a rigid wall that is moving in opposite direction with a constant speed 2m/s. Assuming elastic impact between the particle and wall find the work done by the wall in reflecting the particle.

17.A bead of mass 2m can slide on a smooth rod . A particle of mass m is attached to the bead by a light string of length l. Initially the particle is held horizontally in level with the bead and the string held just taut. If the distance through which the bead will move when the string has turned through an angle is x/30 with the horizontal,, then find the value of x (in SI units)?

[take θ=60°,l=lm ]

18. A particle moves in a circle of radius R with a constant speed v. then, find the magnitude of

average acceleration during a time interval∏R/2v .

Take v=√2∏ and R=√2.

19. An elastic ball of mass 1/2 kg is suspended from a fixed point by an inextensible string. A small particle of same mass moving ’downwards at an angle of 37° with the vertical hits the ball directly with the velocity 17m/s if the coefficient of restitution is 4/5 then determine the impulsive tension (i.e; impulse) in the string at the instant of collision.

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matrix match type (paper-II)

by physics on April 22, 2010

This section contains 2 questions Each question contains statements .

Given in two columns which have

to be matched. The statements in column are labeled A ,B, C and D while the statements in Column are labeled p, q, r and s.

Any given statement in column I can have correct matching with one or more statement(s) in column II. The appropriate bubbles corresponding to the answers to these questions have to be appropriately bubbled as illustrated in the following example. If the correct matches are A-p. B’p, 8-q, B-s, C-p, C-r, and D-q, then the correctly bubbled matrix should be as shown.

10. A disc of radius R is rolling with angular velocity ω angular accelerationα and linear acceleration a along x-direction. There are 4 points A, B, C and D on the disc as shown.

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multiple correct answer type (paper-II)

by physics on April 22, 2010

This section contains 5 multiple correct answer(s) type questions each question has 4ioice (a), (b), (C) and (d). out of which ONE or MORE are correct.

5. Smooth inclined plane has anarg1e of inclination θ from the horizontal. From point A on the inclined plane, body 1 is projected horizontally with speed u and from point B on the inclined plane, body 2 is released from rest. Distance AB is equal to 1. If the magnitude of relative velocity of body 2 w.r.t. body 1 and magnitude of relative acceleration of body 2 w.r.t. body 1 at time t are v and ‘a’, respectively, then which of the following is/are true?

6. A square plate lies in the X-Y plane with its centre at the origin and its edges parallel to the X-Y axes. The moments of inertia about the X-Y-Z axes are I_X, I_Y and I_Z respectively and I_D is the moment of inertia about its diagonal. Then

7. When an air bubble rises from the bottom of a deep lake to a point just below the water surface, the pressure of air inside the bubble

(a) is greater than the pressure outside it

(b) is less than the pressure outside it (c) increases as the bubble moves up

(d) decreases as the bubble moves up

8. A particle of mass m is at rest in a train moving with constant velocity with respect to ground. Now the particle is accelerated by a constant force F₀ acting along the direction of motion of train for time t₀. A girl in the train and a boy on the ground measure the work done by this force. Which of the following are incorrect?

(a) Both will measure the same work.

(b) Boy will measure higher value than the girl.

(d) Data are insufficient for the measurement of work done by the force F₀.

9. A trolley filled with sand moves on a smooth horizontal surface with a velocity v₀. A small hole. is made at the base of it from which sand is leaking out at constant rate. As the sand leaks out

(a) the velocity of the trolley increases

(b) the velocity of the trolley remains constant

(d) the momentum of the total system (trolley + leaked out sand) is conserved.

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straight objective type (paper-II)

by physics on April 22, 2010

This section contains 4 multiple choice questions. Each question has 4 choices (a), (b), (c) and (d), out of which ONLY ONE is correct.

1. In the arrangement shown in figure below, the two pulleys are fixed and two blocks A arid B are made to move downwards so that they decelerate at 10 m/s². The arrangement achieving the above is not shown in the diagram. The block C, which is fixed to the middle of the string, moves upward with a constant velocity u. At a certain instant, (shown in the figure) = 30⁰, and

(dθ/dt)=+1radian/s. It can be concluded that

2. A disc is given an initial angular velocity ωο and placed on rough horizontal surface as shown. The quantities which will not depend on the coefficient of friction is/are

(a) the time until rolling begins.

(b) the displacement of the ‘disc until rolling begins

(d) the work done by the force of friction

3. Liquid density ρ of is filled in the container of negligible mass having area A. Area of hole ‘a’ very small (a <<A) is made near the bottom in the wall of container. Co-efficient of friction between container and surface is equal to(a/A) . As liquid is coming out of vessel, instantaneous acceleration of the container is

4. Figure shows a planar right angled triangle of mass m. What is the moment of inertia of ΔABC about an axis passing through B and perpendicular to the plane?

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matrix match type(paper-1)

by physics on April 22, 2010

This section contains 2 questions. Each question contains statements given in two columns which have to be matched. The statements in column I are labeled A, B, C and D, while the statements in Column II are labeled p. q, r, and s. Any given statement in column I can have correct matching with ONE or MORE statement(s) in column ll. The appropriate bubbles corresponding to the answers to these questions have to be appropriately bubbled as illustrated in the following example. If the correct matches are A-p, B-p, B-q, B-s, C-p. C-r, and D-q, then the correctly bubbled matrix should be as shown above.

19. A system of blocks is placed on a smooth horizontal plane, as shown. For a particular value of F, 3 kg block is’just’about to leave ground

(tan 37⁰=3/4,g=10m/sec²).

20. A particle of 500 g mass moves along a horizontal circle pf radius 16 m such that normal acceleration of particle varies with time as a_x=9t².

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comprehension based questions(paper-I)

by physics on April 22, 2010

This Section contains 2paragraphs. Based upon each paragraph, 3 multiple choice questions have to be answered.

Each question has 4 choices(a), (b), (c) and (d), out of which

ONLY ONE is correct.

comprehension-1

A uniform cylinder of radius R is spinned about its axis to the angular velocity and then placed into a

corner. The coefficient of friction between the corner walls and the cylinder is .

13.The number of revolutions before the cylinder stops is.

14. The function on horizontal wall varies with time as

15. The ratio of friction force on the vertical and horizontal wall is

Comprehension-II

Two holes each of area ‘a’ drilled in the wall of a vessel filled with liquid as shown in the figure. The point P is the point where the streams flowing out of the holes intersect. The level of water is maintained in the vessel by regulated supply.

16. The x-coordinate where the streams flowing out of the holes intersect is

17. The y-coordinate where the streams flowing out of the holes intersect is

18. Time taken by a drop of liquid flowing out of upper hole to reach the .point P is t₁ and, time taken by .a drop of liquid flowing out of lower hole to reach the point P is t₂ • Then the ratio of

t₁ and t₂ is

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multiple correct answer type questions(PAPER-1)

by physics on April 22, 2010

This sèction contain 4 multiple correct answer(s) type questions. Each question has 4 choices (a), (b), (c) and (d), out of which ONE or-MORE are correct is/are correct.

9. water coming out of a horizontal tube at a speed strikes normally a vertically wall close to the mouth of the tube and falls down vertically after impact. When he speed of water is increased to .

(a) The thrust exerted by water on the wall

will be doubled

(b) The thrust exteerted by the water on the wall will be four times ‘ -‘

(d) The energy lost per second by water striking the wall will be increased eight times.

1O. A block is thrown with. a velocity of 2 m s^-1 (relative to ground)on a belt which is moving with velocity 4 m s^-1 in opposite direction of the initial velocity of block. If the block stops slipping on the belt after 4 sec of the throwing then choose the correct statement (s)

(a) Displacement with respect to ground is zero after 2.66 sec and magnitude of displacement with respect to ground is 12h after 4sec

(b) Magnitude of displacement with respect to ground in 4sec is 4m

(d) Displacement with respect to ground is zero in 8/3 sec

11.Heat is supplied to a certain homogeneous sample of matter at a uniform rate. Its temperature is plotted against time as shown in figure which of the following conclusion can be drawn.?

(a) Its specific heat capacity is grater in the solid than in the liquid state

(b). Its specific heat capacity is greater in the liquid state than in the solid state

(d) Its latent of vaporization is smaller than its latent heat of fusion.

12. A machine, in an amusement park, consists of a cage at the end of one arm, hinged at O. The cage revolves along a-vertical circle of radius r(ABCDEFGH) about its hinge , at constant linear speed . The case is so attached that the man of weight ‘w’ standing on a weighing machine, inside the cage, is always vertical. Then which of the following is correct

(a) the weight reading at A is greater than the weight reading at E by 2w

(b) the weight reading at G = w

(d) the ratio of the weight reading at A to that at C = 2.

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IIT-JEE(11-4-2010) . straight objective type(paper-I)

by physics on April 22, 2010

This section contains 8 multiple choice questions. Each question has 4 choices {a), (b), (c) and (d), out of which ONLY ONE is correct.

1. A U-tube containing a liquid is accelerated horizontally with a constant acceleration equal to g/5 where g is the acceleration due to gravity. The separation between the vertical limbs l, while the initial level of the liquid in each arm is also 1, The difference in the heights of liquid in two vertical limbs is, in the steady state,

2. A thin uniform spherical shell and a uniform solid cylinder of the same mass and radius are allowed to roll down a fixed incline, without slipping, starting from rest. The times taken by them to roll down the same distance are in the ratio,

3.A planet of radius R has an acceleration due to gravity of g on its surface. A deep smooth tunnel is dug on this planet, radially inward, to reach a point P 1ocatec at a distance of R/2 from the centre of the planet. Assume that the planet has uniform density. The kinetic energy required to be given to a small body of mass m, projected radially

outward from P, so that it gains a maximum altitude equal to the thrice the radius of the planet from its surface, is equal to

4. A horizontal uniform beam AB of length 4 m and a mass of 20 kg is supported at the end B by means of a string which passes over a fixed, smooth pulley supporting a counterbalancing weight of 8 kg on the other side. What force, F, when applied at the point A in suitable direction, will hold the beam in static equilibrium?

(d) no. force F, as specified, can hold the beam in static equilibrium

5. Two identical spheres A and B each of mass M and radius R are moving on a horizontal surface as shown. The angular momentum of the sphere A about the topmost point of the sphere B is

6. A vessel contains oil’(density0.8 g/cc) over mercury ‘(density 13.6 g/cc). A homogeneous sphere floats with half its volume immersed in mercury and other half in oil. The density of the material of

Sphere in g/cc is

(a)3.3 (b)6.4 (c)7.2 (d)22.8

7. Block A of mass M in the figure is released from the rest when the extension in the spring is x₀. The maximum downward displacement of the block is

8. Velocity-time graph of a particle moving in a straight line is shown in the figure. Mass of the particle is 2kg. Work done by all the forces acting on the particle in time interval t =0 to t = 10 sec is

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CBSE Maths notes, CBSE physics notes, CBSE chemistry notes

BRAIN BOOSTERS

AIEEE (25-4-2010) paper

Integer type questions(paper-II)

matrix match type (paper-II)

multiple correct answer type (paper-II)

straight objective type (paper-II)

matrix match type(paper-1)

comprehension based questions(paper-I)

comprehension-1

Comprehension-II

multiple correct answer type questions(PAPER-1)

IIT-JEE(11-4-2010) . straight objective type(paper-I)

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