Perfume is a GAS when vaporized but is usually packed and sprayed as a liquid.
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Multiple Choice Questions
Q1. Standard Temperature and Pressure (STP) values are most often used for gases as their characteristics change dramatically with temperature and pressure. Which of the following set has correct values of STP?
A. 0 Kelvin and 1 atmosphere
B. 273 Kelvin and 0 atmosphere
C. 273 Kelvin and 760 atmospheres
D. 273 Kelvin and 1 atmosphere
Ans.: D. 273 Kelvin and 1 atmosphere
Q2. Which one of the following graphs correctly represents Boyle’s Law?
A. I
B. II
C. III
D. IV
Ans.: B. II
Q3. Each of the football shown below is of different sizes filled with the same number of gas molecules. Which football has the highest pressure?
A. I
B. II
C. III
D. IV
Ans.: A. I
Q4. “At constant pressure, the volume of a given quantity of a gas increases or decreases by 1/273 of its volume at 0 ºc for rise or fall in the temperature by 1 ºC.” The above law is
A. Boyle’s law
B. Charles’ law
C. Combined gas law
D. Avogadro’s law
Ans.: B. Charles’ law
Q5. The flask A, B, C, and D contain equal number of oxygen molecules. Identify the flask with the highest pressure.
A. Flask A
B. Flask B
C. Flask C
D. Flask D
Ans.: A. Flask A
Q6. A certain mass of gas occupies a volume of 3.0L at 90 atm. What pressure would the gas exert if it were placed in a 9L container at the same temperature?
A. 0.03 atm
B. 0.32 atm
C. 3.0 atm
D. 30 atm
Ans.: D. 30 atm
Q7. Charles’ law is based on the relationship between
A. volume and density.
B. pressure and volume.
C. volume and temperature.
D. pressure and temperature.
Ans.: C. volume and temperature.
Q8. An inflated balloon bursts when you sit on it. This phenomenon involves
A. Boyle’s law.
B. Charles’ law.
C. Ideal Gas law.
D. Avogadro’s law.
Ans.: A. Boyle’s law
Q9. Dorji places a balloon inside the refrigerator that has a temperature of 10 ºC. Interpret the value in Kelvin.
A. 263 K
B. 273 K
C. 283 K
D. 293 K
Ans.: C. 283 K
Q10. What inference can you draw when the plunger of the syringe filled with air is pushed in?
A. pressure increases, volume decreases
B. pressure decreases, volume increases
C. pressure increases, volume increases
D. pressure decreases, volume decreases
Ans.: B. pressure decreases, volume increases
Q11. “Equal volume of all gases under the same conditions of temperature and pressure contain the same number of molecules”. The above law refers to
A. Avogadro’s law.
B. Boyle’s law.
C. Charles’ law.
D. Gay Lussac’s law.
Ans.: A. Avogadro’s law
Q12. Mindu filled a balloon with 14L of hydrogen gas, then he reduced the pressure to 4 atmospheres and found out that the balloon expanded to occupy double the initial volume. What was the initial pressure exerted on the balloon?
A. 2 atm
B. 4 atm
C. 6 atm
D. 8 atm
Ans.: D. 8 atm
Short Questions
Q1. Fill in the blanks.
i) In gas law syringe and marshmallow are used to determine relationship between volume and ________________.
Ans.: pressure
ii) ________________ is the combination of Boyle’s law, Charles’ law and Avogadro’s law.
Ans.: Ideal Gas Law
Q2. Write the difference between the following pairs.
a. Boyle’s law and Charles’ law (formula)
Ans.:
| Boyle’s law | Charles’ law |
| P1V1 = P2V2 | V1/T1= V2/T2 |
b. Boyle’s law and Charles’ law (Definition)
Ans.:
| Boyle’s law | Charles’ law |
| The volume of a gas is inversely proportional to pressure at constant temperature. | The volume of a gas is directly proportional to absolute temperature at constant pressure. |
Q3. The volume occupied by 1 mole of helium is 22.4 L at STP. What would be the volume occupied by 1 mole of oxygen at STP?
Ans.: 22.4 L or 22400 cm3
Q4. What would happen to the volume of 10L Carbon dioxide, if the pressure is doubled and the temperature is kept constant?
Ans.: The volume of carbon dioxide would decrease by half (5 litres).
Q5. Mention any two variables of Ideal Gas law.
Ans.: Pressure, volume, or temperature
Q6. A balloon filled with hydrogen gas is left inside a car, on a hot summer day. What would happen to the volume and pressure of hydrogen gas?
Ans.: Temperature increases inside a car (in hot summer day) and that expands the space between gas molecules inside the balloon. Due to this, the volume of balloon increases. The volume is indirectly proportional to pressure, hence the pressure decreases.
Q7. The Table given below shows the behavior of a gas at constant temperature. Study it carefully and answer the following questions.
| Volume (L) | Pressure (atm) |
| 2 | 4 |
| 4 | 3 |
| 6 | 2 |
| 8 | 1 |
a. What happens to the volume of the gas as the pressure increases?
Ans.: Volume decreases
b. Write down the relationship between pressure and volume of a gas at constant temperature.
Ans.: Volume is inversely proportional to the pressure.
Numerical Questions
Q1. A sample of a gas at 1 atmosphere has volume of 1.5 L. What would be its volume at 5 atmosphere pressure?
Ans.:
Q2. A gas occupies 4.2 L at 1atm and 300K. Determine the volume occupied at 293K and 420 mm Hg.
Ans.:
Q3. A vessel contains 2.6 L of gas at 1200 mm Hg. If the pressure of the gas is doubled, what would be the new volume at the same temperature?
Ans.:
Q4. A balloon with a volume of 2.0 L is filled with a gas at 3 atmosphere. If the pressure is reduced to 0.5 atmosphere, without the change in temperature what would be the volume of the balloon?
Ans.:
Q5. A sample of hydrogen has an initial temperature of 50°C.When the temperature is lowered to 10°C, the volume of hydrogen becomes 2L. What was the initial volume of hydrogen?
Ans.:
Q6. During Kabita’s birthday, 10 balloons were filled with 6L of hydrogen gas. The pressure inside was reduced to 1 atmosphere and the balloon expanded to occupy a volume of 20L. Calculate the initial pressure exerted on the balloon.
Ans.:
Q7. Dhan Maya was playing with a balloon having a volume of 6L of air at 25⁰C. She wanted to hide it from her sister by keeping it inside the refrigerator kept at a temperature of 4⁰C. Calculate the volume of the air inside the balloon at the time of taking it out from the refrigerator.
Ans.:
Q8. 6.2 L of an ideal gas are contained at 3.0 atm and 37°C. How many moles of this gas is present in the container? [Use R=0.08 L atm K-1mol-1]
Ans.:
Compiled from BCSE 2017-2021