Chemistry

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Option (ii). Adding salt to water and

(iv). Decreasing the temperature of water

By adding salt to water,   the water molecule available at the surface to evaporate will be low and hence, the vapour pressure decreases. Also vapour pressure is directly proportional to temperature so when we decrease the temperature of water the vapour pressure decreases. 

This is a multiple choice answer as classified in NCERT Exemplar

option (ii). High pressure and

(iii). Low temperature

The real gases obey the ideal gas equation, PV= nRT at low pressure and high temperature. So, a gas does not obey the ideal gas equation or behave ideally at high pressure and low temperature.

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Option (i).  16 grams of gas and

(iv). 11.2 litres of gas 

1 mole of dioxygen at STP  occupies   =  22.4 L    

molar mass of dioxygen  =   32 g 

contain  6.023*10²³ molecules of  oxygen gas 

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Option (ii). Complete disorder of molecules and

(iii). Random motion of molecules 

In a gaseous state of matter, molecules are arranged in complete disorder and  they move in random motion in all directions.

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Option (ii).  Decreases

When the temperature increases, kinetic energy of the molecule increases which leads to decrease in the intermolecular forces and hence, decreases the surface tension. 

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Option (iii) Decrease 

The increase in temperature increases the kinetic energy which can overcome intermolecular forces of attraction due to which the viscosity decreases and the liquid starts flowing. 

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Option (i). B only 

For all ideal gas PV = constant. Only B has no change with the change in PV, so only line B represents the curve of ideal gas.

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option (i). Shimla 

The temperature at which the liquid boils when the vapour pressure becomes equal to the atmospheric pressure  is known as the boiling point of the liquid. When the  atmospheric pressure is low, the boiling point of the liquid will be low. As Shimla has the lowest atmospheric pressure, it will boil first.

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option (ii) Nsm^-2 

viscosity coefficient (η) = $\frac{Force}{Area*VelocityGradient}$

SI unit of (η)= Nsm^-2

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Option (iv) O₂, N₂, H₂, He

Higher the critical temperature of gases more easily, the gas will be liquefied. So, the order of liquefying of gases will be  O₂ > N₂ > H₂ >He.