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
rotation.

Note: Multiple alternatives possible.

2.
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

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.