# NCERT Solutions for Class 11 Chemistry Chemistry Part-1 Chapter 5

## States of Matter Class 11

### Exercise : Solutions of Questions on Page Number : 152

Q1 :

What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?

Given,

Initial pressure, p1 = 1 bar

Initial volume, V1 = 500 dm3

Final volume, V2 = 200 dm3

Since the temperature remains constant, the final pressure (p2) can be calculated using Boyle's law.

According to Boyle's law, Therefore, the minimum pressure required is 2.5 bar.

Q2 :

A vessel of 120 mL capacity contains a certain amount of gas at 35 °C and 1.2 bar pressure. The gas is transferred to another vessel of volume 180 mL at 35 °C. What would be its pressure?

Given,

Initial pressure, p1 = 1.2 bar

Initial volume, V1 = 120 mL

Final volume, V2 = 180 mL

Since the temperature remains constant, the final pressure (p2) can be calculated using Boyle's law.

According to Boyle's law, Therefore, the pressure would be 0.8 bar.

Q3 :

Using the equation of state pV = nRT; show that at a given temperature density of a gas is proportional to gas pressurep.

Q4 :

At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

Q5 :

Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes 3 bar. Find a relationship between their molecular masses.

Q6 :

The drain cleaner, Drainex contains small bits of aluminum which react with caustic soda to produce dihydrogen. What volume of dihydrogen at 20 °C and one bar will be released when 0.15g of aluminum reacts?

Q7 :

What will be the pressure exerted by a mixture of 3.2 g of methane and 4.4 g of carbon dioxide contained in a 9 dm3 flask at 27 °C ?

Q8 :

What will be the pressure of the gaseous mixture when 0.5 L of H2 at 0.8 bar and 2.0 L of dioxygen at 0.7 bar are introduced in a 1L vessel at 27°C?

Q9 :

Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?

Q10 :

34.05 mL of phosphorus vapour weighs 0.0625 g at 546 °C and 0.1 bar pressure. What is the molar mass of phosphorus?

Q11 :

A student forgot to add the reaction mixture to the round bottomed flask at 27 °C but instead he/she placed the flask on the flame. After a lapse of time, he realized his mistake, and using a pyrometer he found the temperature of the flask was 477 °C. What fraction of air would have been expelled out?

Q12 :

Calculate the temperature of 4.0 mol of a gas occupying 5 dm3 at 3.32 bar.

(R = 0.083 bar dm3 K-1 mol-1).

Q13 :

Calculate the total number of electrons present in 1.4 g of dinitrogen gas.

Q14 :

How much time would it take to distribute one Avogadro number of wheat grains, if 1010 grains are distributed each second?

Q15 :

Calculate the total pressure in a mixture of 8 g of dioxygen and 4 g of dihydrogen confined in a vessel of 1 dm3 at 27°C. R = 0.083 bar dm3 K-1 mol-1.

Q16 :

Pay load is defined as the difference between the mass of displaced air and the mass of the balloon. Calculate the pay load when a balloon of radius 10 m, mass 100 kg is filled with helium at 1.66 bar at 27°C. (Density of air = 1.2 kg m-3 and R = 0.083 bar dm3 K-1 mol-1).

Q17 :

Calculate the volume occupied by 8.8 g of CO2 at 31.1°C and 1 bar pressure.

R = 0.083 bar L K-1 mol-1.

Q18 :

2.9 g of a gas at 95 °C occupied the same volume as 0.184 g of dihydrogen at 17 °C, at the same pressure. What is the molar mass of the gas?

Q19 :

A mixture of dihydrogen and dioxygen at one bar pressure contains 20% by weight of dihydrogen. Calculate the partial pressure of dihydrogen.

Q20 :

What would be the SI unit for the quantity pV2T 2/n?

Q21 :

In terms of Charles' law explain why -273°C is the lowest possible temperature.

Q22 :

Critical temperature for carbon dioxide and methane are 31.1 °C and -81.9 °C respectively. Which of these has stronger intermolecular forces and why?