#### Gaseous State - Important Question Paper

11th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 50

Part A

10 x 1 = 10
1. Which of the following is the correct expression for the equation of state of van der Waals gas?

(a)

$\left( P+\frac { a }{ { n }^{ 2 }{ V }^{ 2 } } \right) (V-nb)=nRT$

(b)

$\left( P+\frac { na }{ { n }^{ 2 }{ V }^{ 2 } } \right) (V-nb)=nRT$

(c)

$\left( P+\frac { { an }^{ 2 } }{ { V }^{ 2 } } \right) (V-nb)=nRT$

(d)

$\left( \frac { P+{ n }^{ 2 }{ a }^{ 2 } }{ { V }^{ 2 } } \right) (V-ab)=nRT$

2. When an ideal gas undergoes unrestrained expansion, no cooling occurs because the molecules

(a)

are above inversion temperature

(b)

exert no attractive forces on each other

(c)

do work equal to the loss in kinetic energy

(d)

collide without loss of energy

3. Equal weights of methane and oxygen are mixed in an empty container at 298 K. The fraction of total pressure exerted by oxygen is

(a)

$\frac { 1 }{ 3 }$

(b)

$\frac { 1 }{ 2 }$

(c)

$\frac { 2 }{ 3 }$

(d)

$\frac { 1 }{ 3 } \times 273\times 298$

4. The value of universal gas constant depends upon

(a)

Temperature of the gas

(b)

Volume of the gas

(c)

Number of moles of the gas

(d)

units of Pressure and volume.

5. The value of the gas constant R is

(a)

0.082 dm2 atm.

(b)

0.987 cal mol-1K-1

(c)

8.3 J mol-1 K-1

(d)

8 erg mol-1 K-1

6. 25g of each of the following gases are taken at 27°C and 600 mm Hg pressure. Which of these will have the least volume?

(a)

HBr

(b)

HCI

(c)

HF

(d)

HI

7. When the volume of agas is plotted versus the celsius temperature with pressure and number of moles held constant, the x-intercept is at what temperature?

(a)

00C

(b)

-2730C

(c)

The boiling point of the gas

(d)

The melting point of the gas

8. A balloon has maximum capacity of 20 L. at one atmospheric pressure, 10 L of air is filled in the ballon. it will burst when pressure is (assuming isothermal condition)

(a)

0.5 atm

(b)

0.4 atm

(c)

0.7 atm

(d)

0.8 atm

9. Given J-tube has 2.4 mL o air is reduced to 1.9mL as shown. Difference in the level of mercury in two columns is

(a)

700 mm

(b)

200 mm

(c)

900 mm

(d)

760 mm

10. A person living in shimla observed that cooking food without using pressure cooker takes more time , The reason  for this observation is that at high altitude

(a)

pressure increase

(b)

temperature decrease

(c)

pressure decrease

(d)

Temperature increases

11. Part B

9 x 2 = 18
12. Write a short note on the consequence of Boyle's law. (or) Give the relationship between pressure and density

13. Define absolute zero. Is it possible to attain a further lower temperature? Comment on your answer.

14. Define the terms isotherm, isobar and isochore.

15. Defind pressure. Give its units.

16. A gas is enclosed in a room. The pressure, density, temperature and number of moles are p atm, g cm-3, t °C and n moles respectively. What will be the pressure, temperature, density and number of moles, in each compartment. if room is partitioned into four equal compartments?

17. State Gay Lussac's law.

18. Define atmospheric pressure. What is its value?

19. Most aeroplanes cabins are artificially pressurized. Why?

20. Define inversion temperature.

21. Part C

4 x 3 = 12
22. State Boyle's law.

23. A balloon filled with air at room temperature and cooled to a much lower temperature can be used as a model for Charle's law.

24. Give the mathematical expression that relates gas volume and moles. Describe in words what the mathematical expression means.

25. What are ideal gases? In what way real gases differ from ideal gases.

26. Part D

2 x 5 = 10
27. An inflated balloon has a volume of 275 mL, and contains 0.120 mole of air. As shown in fig a piece of dry ice weighing 1 g is placed in the balloon and its neck is tied. What is the volume of the balloon after dry ice (solid CO2) has vaporized? Assume pressure and temperature to remain constant.

28. Argon is an inert gas used in light bulbs to retard the vaporization of the tungsten filament. A certain light bulb containing argon at 1.2 atm and 18°C is heated to 85°C at constant volume. Calculate its final pressure in atm.