Sunday, September 30, 2007

Questions for 1-10-2007

1. In a dark room with ambient temperature T0, a black body is kept at a temperature T. Keeping the temperature of the black body constant (at T), sunrays are allowed to fall on the black body through a hole in the roof of the dark room. Assuming that there is no change in the ambient temperature of the room, which of
the following statement(s) is/are correct?

(A) The quantity of radiation absorbed by the black body in unit time will increase.
(B) Since emissivity = absorptivity, hence the quantity of radiation emitted by black body in unit time will increase.
(C) Black body radiates more energy in unit time in the visible spectrum.
(D) The reflected energy in unit time by the black body remains same.

2. The smallest ketone and its next homologue are reacted with NH-2OH to form oxime.

(A) Two different oximes are formed
(B) Three different oximes are formed
(C) Two oximes are optically active
(D) All oximes are optically active

3. If 0 < θ < 2π, then the intervals of values of θ for which 2 sin^2θ − 5 sinθ + 2 > 0, is

A. (0,π/6)∪(5π/6, 2π)
B. (π/8, 5π/6)
C. (0,π/8)∪(π/6, 5π/6)
D. (41π/48, π)

Answers for 30-9-2007

1. A - P
B - R
C - R
D - P, Q, S

2. C

3. D

Saturday, September 29, 2007

IIT JEE Questions for 30-9-2007

1. A simple telescope used to view distant objects has eyepiece and objective lens of focal lengths fe and f0,
respectively. Then

Column I------------------------------------------ Column II
(A) Intensity of light received by lens---------- (P) Radius of aperture (R)
(B) Angular magnification------------------------ (Q) Dispersion of lens
(C) Length of telescope-------------------------- (R) focal length f0, fe
(D) Sharpness of image--------------------------- (S) spherical aberration

2. The IUPAC name of C-6H-5COCl is

(A) Benzoyl chloride
(B) Benzene chloro ketone
(C) Benzene carbonyl chloride
(D) Chloro phenyl ketone

3. Integral of [(x^2-1)/(x^3*(SQRT(2x^4-2x^2+1))]

(A) [(SQRT(2x^4-2x^2+1)/x^2] + c
(B) [(SQRT(2x^4-2x^2+1)/x^3] +c
(C) [(SQRT(2x^4-2x^2+1)/x] + c
(D) [(SQRT(2x^4-2x^2+1)/2x^2] + c

Answers for the questions of 29-9-2007

1. A,B,D

2. A----P,R

3. C,D

Friday, September 28, 2007

Question for the Day 29.9.2007

1. Function x = A sin^2 ωt + B cos^2 ωt + C sin ωt cos ωt represents Simple Harmonic Motion

(A) for any value of A, B and C (except C = 0)
(B) if A = −B; C = 2B, amplitude = Absolute value of (B*SQRT(2))
(C) if A = B; C = 0
(D) if A = B; C = 2B, amplitude = Absolute value of B

Multiple solutions possible

2. . Match the extraction processes listed in Column I with metals listed in Column II:
Column I --------------------------------- Column II
(A) Self reduction -------------------------- P. Lead
(B) Carbon reduction-------------------------- Q. Silver
(C) Complex formation and -------------------- R. Copper
displacement by metal
(D)Decomposition of iodide-------------------- S. Boron

3. A tangent drawn to the curve y = f(x) at P(x, y) cuts the x-axis and y-axis at A and B respectively such that BP : AP = 3:1, given that f(1) = 1, then

(A) equation of curve is x(dy/dx) - 3y = 0
(B) normal at (1, 1) is x + 3y = 4
(C) curve passes through (2, 1/8)
(D) equation of curve is x(dy/dx)+3y = 0

Note: multiple solutions possible

Answers for Questions of 28/9/2007

1. C and D

2. A

3. A

Thursday, September 27, 2007

Questions fo 28-9-=2007

1. A solid cylinder of mass m and radius r is rolling on a rough inclined plane of inclination θ. The coefficient of friction between the cylinder and incline is μ. Then

(A)frictional force is always μmg cos θ
(B)friction is a dissipative force
(C)by decreasing θ, frictional force decreases
(D)friction opposes translation and supports

Note: Multiple alternatives possible.

The coordination number of Ni(2+) ion is 4.

NiCl-2 + KCN (excess) → A (cyano complex)
NiCl-2 + Conc. HCl (excess) → B (chloro complex)

The IUPAC name of A and B are
(A) Potassium tetracyanonickelate (II), potassium tetrachloronickelate (II)
(B) Tetracyanopotassiumnickelate (II), teterachlorpotassiumnickelate (II)
(C) Tetracyanornickel (II), tetrachloronickel (II)
(D) Potassium tetracyanonickel (II), potassium tetrachloronickel (II)

3. Let a, b, c be the sides of a triangle. No two of them are equal and λ ∈ R. If the roots of the equation x^2 + 2(a + b+ c) x
+ 3λ (ab + bc + ca) = 0 are real, then
(A) λ < 4/3
(B) λ > 5/3
(C)λ can be any value between 1/3 and 5/3
(D)λ is higher than 4/3 but less than 5/3

Answers for Q of 27-9-2007

1. A

2. D

3. C

Question for the Day 27-9-2007

1. A solid sphere of mass M, radius R and having moment of inertia about an axis passing through the centre of mass as I, is recast into a disc of thickness t, whose moment of inertia about an axis passing through its edge and perpendicular to its plane remains I. Then, radius of the disc will be

(A) 2R/SQRT(15)

(B) R*SQRT(2/15)

(C) 4R/SQRT(15)

(D) R/4

2. CuSO-4 decolourises on addition of KCN, the product is

(A) Cu(CN)-4 (B) [Cu(CN)-3
(C) Cu(CN)-2 (D) CuCN

3. Given an isosceles triangle, whose one angle is 120° and radius of its incircle = SQRT(3) . Then the area of the triangle in sq.units is

(A) 7 + 12*SQRT(3) (B) 12 − 7*SQRT( 3)

(C) 12 + 7*SQRT( 3) (D) 4π

Tuesday, September 25, 2007

Answers to Q of 26-9-2007

1. B

2. A

3. C

Question for the Day 26-9-2007

1. A biconvex lens of focal length f forms a circular image of sun of radius r in focal plane. Then
(A) πr^2 ∝ f
(B) πr^2 ∝ f^2
(C) if lower half part is covered by black sheet, then area of the image is equal to πr^2/2
(D) if f is doubled, intensity will increase

2.MgSO-4 on reaction with NH-4OH and Na-2HPO-4 forms a white crystalline precipitate. What is its formula?

(A) Mg(NH-4)PO-4
(B) Mg-3(PO-4)-2
(C) MgCl-2.MgSO-4
(D) MgSO-4

3. For x > 0, Lim[(Sin)^(1/x)+(1/x)^sinx)] is
(x -> 0)
(A) 0
(B) -1
(C) 1
(D) 2

Answers for Q for 25-9-2007

1. C

2. A

3. A

Questions for the Day 25-9-2007

1. Orthocentre of triangle with vertices (0, 0), (3, 4) and (4, 0) is
(A) (3, 5/4)
(B) (3, 12)
(C) (3, 3/4)
(D) (3, 9)

2. During depression of freezing point in a solution the following are in equilibrium
(A) liquid solvent, solid solvent (B) liquid solvent, solid solute
(C) liquid solute, solid solute (D) liquid solute solid solvent

3. A cube has a side of length 1.2 × 10^−2m. Calculate its volume.
(A) 1.7 × 10^−6 m^3. (B) 1.73 × 10^−6 m^3.
(C) 1.70 × 10^−6 m^3. (D) 1.732 × 10^−6 m^3.