Kinetic molecular theory of gases

Answer Key - Grade 10 Science Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   A sealed balloon warms from 25 °C to 50 °C. By what factor does the particles' average kinetic energy change, to 0.01, Esme?

   1.08 times
2. 2.

   A car tire's air warms from 15 °C to 45 °C on a hot day. By what factor does the average kinetic energy change, to 0.01, Jun?

   1.1 times
3. 3.

   At the same temperature, which moves faster on average: O₂ (32.00 g/mol) or CO₂ (44.01 g/mol), Kira?

   • O₂, since lighter particles move faster at equal energy
   • CO₂, since heavier particles move faster and hit the walls harder
   • Neither: equal temperature means equal speed
4. 4.

   At 25 °C, do the particles in a balloon all move at the same speed, Milo?

   • No: speeds vary, and temperature sets the average
   • Yes, if the balloon holds a single gas
   • Yes: a single temperature means a single speed for each particle
5. 5.

   When does a real gas act most like kinetic theory's ideal gas, Noah?

   • Just at exactly 0 °C
   • At high pressure and low temperature
   • At low pressure and high temperature
6. 6.

   Why do real gas particles stop acting ideal when squeezed very hard, Pia?

   • Their own size and attractions start to matter
   • They stop moving under pressure
   • They grow larger as pressure rises
7. 7.

   Steam from a kettle cools and condenses into drops. Which kinetic-theory idea has broken down, Ren?

   • That particles do not attract each other
   • That particles are in constant motion
   • That particles take up little space
8. 8.

   A balloon left in a freezer shrinks. Why, Tala?

   • The particles stop moving and fall
   • Slower particles hit the rubber less hard and less often
   • The particles shrink in the cold, so they fill less of the space
9. 9.

   A car tire's pressure rises after a drive on a hot day. Why, Zee?

   • The heat adds new particles to the tire
   • The particles swell in the heat and press harder on the walls
   • Faster particles hit the tire walls harder and more often
10. 10.

    A sealed syringe is warmed in a hand, and its plunger slides out. Why, Ari?

    • The hand pushes air in through the seal
    • Faster particles hit the plunger more
    • The particles grow and push the plunger