Gases Practice Problems

  1. Which of the following is the correct expression for the ideal gas law?
  1. \(PT = nVR\)
  2. \(VR = nPT\)
  3. \(PV = nRT\)
  4. \(RT = nPV\)
Show Answer
The correct answer is C!

The ideal gas law is \(PV = nRT\), relating pressure, volume, moles, and temperature through the gas constant \(R\).

 

  1. What is the boiling point of water at standard pressure on the Kelvin scale?
  1. 272 K
  2. 273 K
  3. 372 K
  4. 373 K
Show Answer
The correct answer is D!

At 1 atm, water boils at 100°C, which is 373 K (since \(T_\text{K} = T_\text{°C} + 273\)).

 

  1. Which statement is consistent with the kinetic theory of ideal gases?
  1. Molecules transfer energy through collisions.
  2. Molecules are always stationary.
  3. The force of attraction between molecules is constant.
  4. The size of the molecules is large compared to the distance that separates them.
Show Answer
The correct answer is A!

In the kinetic molecular theory, gas particles are in constant random motion and collide elastically, exchanging energy in collisions.

Ideal gases assume negligible intermolecular forces and particle volumes small relative to their separation.

 

  1. Gas molecules at the same temperature are assumed to have the same average:
  1. Uniform velocity
  2. Uniform acceleration
  3. Number of atoms
  4. Kinetic energy
Show Answer
The correct answer is D!

Temperature is proportional to the average translational kinetic energy of molecules. Lighter molecules move faster on average, so velocities are not uniform.

 

  1. As the volume of a fixed mass of an ideal gas increases at constant temperature, the product of the pressure and the volume of the gas
  1. Decreases
  2. Increases
  3. Remains the same
  4. Cannot be predicted
Show Answer
The correct answer is C!

At constant temperature for a fixed amount of gas, \(PV = nRT\) is constant (Boyle’s law).

 

  1. Which property determines the direction of the exchange of internal energy between two objects?
  1. Temperature
  2. Specific heat
  3. Mass
  4. Density
Show Answer
The correct answer is A!

Heat flows spontaneously from higher to lower temperature. Specific heat, mass, and density affect how much energy is exchanged, not the direction.

 

  1. A glass rod becomes positively charged when it is rubbed with silk. This net positive charge accumulates because the glass rod
  1. Gains electrons
  2. Gains protons
  3. Loses electrons
  4. Loses protons
Show Answer
The correct answer is C!

Charging by friction transfers electrons. The glass rod loses electrons to the silk, leaving a net positive charge (protons remain bound in the nucleus).