The colour of the +ve column in a gas discharge tube depends on

• the type of glass used to construct the tube

• the gas in the tube

• the applied voltage

• the material of the cathode

The rms speed of the molecules of a gas in a vessel is 400 ms. If half of the gas leaks out, at constant temperature, the rms speed of the remaining molecules will be

• 800 ms^-1

• $400\sqrt{2} {\mathrm{ms}}^{-1}$

• 400 ms^-1

• 200 ms^-1

An electron tube was sealed off during manufacture at a pressure of 1.2 x 10^-7 mm of mercury at 27°C. Its volume is 100 cm³. The number of molecules that remain in the tube is

• 2 × 10¹⁶

• 3 × 10¹⁵

• 3.86 × 10¹¹

• 5 × 10¹¹

A constant volume gas thermometer works on

• Archimede's principle

• Pascal's law

• Boyle's law

• Charle's law

A sample of ideal monoatomic gas is taken round the cycle ABCA as shown in the figure. The work done during the cycle is

• 3 pV

• zero

• 9 pV

• 6 pV

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

27.

Absorption coefficient of an open window is

• 1

• 0.25

• zero

• 0.5

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

• $\sqrt{8}$

• $\sqrt{2/17}$

• $\sqrt{1/8}$

• $\sqrt{32/17}$

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 %

Which one of the following graphs represents the behaviour of an ideal gas ?