Heavy water is

• compound of deuterium and oxygen

• water at 4°C

• water, in which soap does not lather

• compound of heavy oxygen and heavy hydrogen

Absorption coefficient of an open window is

• 1

• 0.25

• zero

• 0.5

The loudness and pitch of a sound note depend on

• intensity and velocity

• frequency and velocity

• intensity and frequency

• frequency and number of harmonics

In Melde's experiment in the transverse mode, the frequency of the tuning fork and the frequency of the waves in the string are in the ratio

• 2 : 1

• 4 : 1

• 1 : 1

• 1 : 2

Oxygen is 16 times heavier than hydrogen. Equal volumes of hydrogen and oxygen are mixed. The ratio of speed of sound in the mixture to that in hydrogen is

• $\sqrt{8}$

• $\sqrt{2/17}$

• $\sqrt{1/8}$

• $\sqrt{32/17}$

If two waves of the same frequency and amplitude respectively on superposition produce a resultant disturbance ofthe same amplitude, the waves differ in phase by

• $\mathrm{\pi }$

• zero

• $\mathrm{\pi }/3$

• $2\mathrm{\pi }/3$

A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is 340 ms^-1, the distance between the cliffs is

• 680 m

• 1700 m

• 340 m

• 1620 m

Specific rotation of sugar solution is 0.01 SI units. 200 kgm^-3 of impure sugar solution is taken in a polarimeter tube of length 0.25 m and an optical rotation of 0.4 rad is observed. The percentage of purity of sugar in the sample is

• 11 %

• 20 %

• 80 %

• 89 %

Two conductors of the same material have their diameters in the ratio 1 : 2 and their lengths in the ratio 2 : 1. If the temperature difference between their ends is the same, then the ratio of amounts of heat conducted per second through them will be

• 4 : 1

• 1 : 4

• 8 : 1

• 1 : 8

20.

Blowing air with open mouth is an example of

• isobaric process

• isochoric process

• isothermal process

• adiabatic process