Answers for questions of 18-10-2007

1.C
2.A
3.D

Questions for 18-10-2007

1.

Statement - 1

The formula connecting u, v and f for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvature.

Because
Statement - 2

Laws of reflection are strictly valid for plane surfaces, but not for large spherical surfaces

(A) Statement – 1 is True, Statement – 2 is True; Statement – 2 is a correct explanation for
statement – 1
(B) Statement – 1 is True, Statement – 2 is True; Statement – 2 is Not a correct explanation for
Statement – 1.
(C) Statement – 1 is True, Statement – 2 is False
(D) Statement – 1 is False, Statement – 2 is True


2.

Statement - 1
Boron always forms covalent bond

Because
Statement - 2

The small size of B^3+favours formation of covalent bond.

(A) Statement – 1 is True, Statement – 2 is True; Statement – 2 is a correct explanation for statement – 1
(B) Statement – 1 is True, Statement – 2 is True; Statement – 2 is Not a correct explanation for Statement – 1.
(C) Statement – 1 is True, Statement – 2 is False
(D) Statement – 1 is False, Statement – 2 is True

3. Let F(x) be an indefinite integral of sin^2 x.

Statement - 1

The function F(x) satisfies F(x +Pi) = F(x) for all real x.

Because

Statement - 2

sin^2 (x+ Pi) = sin^2 x for all real x.

(A) Statement – 1 is True, Statement – 2 is True; Statement – 2 is a correct explanation for statement – 1
(B) Statement – 1 is True, Statement – 2 is True; Statement – 2 is Not a correct explanation for Statement – 1.
(C) Statement – 1 is True, Statement – 2 is False
(D) Statement – 1 is False, Statement – 2 is True

Answers to Questions of 17-10-2007

1. B

2. A

3. B

Q's for the day 17-10-2007

1. The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm. If a concave lens of focal length 20 cm is placed between the convex lens and the image at a distance of 26 cm from the convex lens, calculate the new size of the image.


(A) 1.25 cm (B) 2.5 cm
(C) 1.05 cm (D) 2 cm





2. Among the following, the molecule with the highest dipole moment is:

(A) CH-3Cl (B) CH-2Cl-2
(C) CHCl-3 (D) CCl-4





3. The number of integral points (integral point means both the coordinates should be integer) exactly in the interior of the triangle with vertices (0, 0), (0, 21) and (21, 0), is

(A) 133 (B) 190
(C) 233 (D) 105

1. Final temperature is 0 degress celsius

2. A

3. 216 or 217 pm

Questions for 2-10-2007

1. In an insulated vessel, 0.05 kg steam at 373 K and 0.45 kg of ice at 253 K are mixed. Then, find the final temperature of the mixture.

Given, L(fusion) = 80 cal/g = 336 J/g, L(vaporization) = 540 cal/g = 2268 J/g,
S(ice) = 2100 J/kg K = 0.5 cal/gK and S(water) = 4200 J/kg K = 1 cal /gK

2. If f″(x) = − f(x) and g(x) = f′(x) and F(x) = [f(x/2)]^2 + [g(x/2)]^2 and given that F(5) = 5 then F(10) is equal to

(A) 5
(B) 10
(C) 0
(D) 15



3. The edge length of unit cell of a metal having molecular weight 75 g/mol is 5
A^0 which crystallizes in cubic lattice. If the density is 2 g/cc then find the radius of metal atom. [N(A) = 6 × 10^23]. Give the answer in pm.

Answers for Questions of 1-10-2007

1. All A,B,C,D

2. B

3. A