Questions for 20-10-2007

1.

Statement - 1
If the accelerating potential in an X-ray tube is increased, the wavelengths of the characteristic X-rays do not change.

Because

Statement - 2
When an electron beams strikes the target in an X-ray tube, part of the kinetic energy is converted into X-ray energy.

(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.
When 20 g of naphthoic acid (C-11 H-8 O-2) is dissolved in 50 g of benzene  [K(f) = 1.72 K kg mol^ -1], a freezing point depression of 2 K is observed. The van’t Hoff factor (i) is

(A) 0.5
(B) 1
(C) 2
(D) 3



3.

Tangents are drawn from the point (17, 7) to the circle x^2 + y^2 = 169.

Statement - 1
The tangents are mutually perpendicular.

Because

Statement - 2
The locus of the points from which mutually perpendicular tangents can be drawn to the given circle is x^2 + y^2 = 338.

(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