LEVEL -1
1. At what condition surface tension vanishes?
Ans: At critical temperature.
2. Why He is used in balloons in place of hydrogen?
Ans: Due to the incombustible nature of He.
3. Below what temp. A gas does not obey ideal gas laws?
Ans: Below Boyle’s Temperature.
4. At what temp. Vol. of a gas is supposed to be zero?
Ans: At 0 K.
5. What is the molar volume of a gas at
bar pressure?
Ans: 22400mL
6. Name the temperature above which a gas cannot be liquefied byany amount of pressure?
Ans: Critical temperature
7. What is the effect of increase of temperature on surface tension and viscosity in a liquid?
Ans: Both decreases with increase in temperature .
8. Why vegetables are cooked with difficulty at hill station?
Ans: At hill station the atmospheric pressure is less and so boiling point decreases.
9. What is the value of Z for an Ideal gas?
Ans: For ideal gas,Z =1.
LEVEL -2
1. What type of graph will you get when P V is plotted against P at constant temperature?
Ans: A straight line parallel to pressure axis.
2. What would have happened to the gas if the molecular collision were not elastic?
Ans: On every collision there is loss of energy, so molecule s would haveslowed downand settled down in vessel and pressure reduce to Zero.
3. At a particular temperature, why vapour pressure of acetone is less than ether?
Ans: Molecular force of attraction in acetone is stronger than those present in ether.
4. Why liquids diffuse slowly as compared to gases?
Ans: In liquids the molecules are less free than in gas i.e intermolecular forces in liquid are greater than in gas.
LEVEL – 3
1. (a) Why aerated water bottle kept under water during summer?
(b) Why do real gases deviate from ideal behaviour?
(c) Why is moist air lighter than dry air?
Ans: (a) To reduce the temperature so as to reduce pressure, otherwise bottle may burst.
(b) Real gas deviate from ideal behavior due to force of attraction and volume of molecules of gases are negligible.
(c) Moist air has water vapours which lower vapour density, so it I lighter.
2. An oxygen cylinder has 10 L oxygen at 200 atm. If patient takes 0.5 mL of oxygen at 1 atm in one breathes at
. How many breaths are possible?
Ans:
4. Why a does sharpened edge become smooth on heating up to melting point?
Ans: On heating the glass it melts & takes up rounded shape at edges which has minimum surface area due to surface tension.
5. Why a liquid drop is spherical in shape?
Ans: A liquid tries to keep minimum no. of molecules in its surface & sphere has minimum surface area.
