1. True or false statements:

• A liquid will sink when it is hotter than the liquid around it. False

• Air becomes less dense and sinks when it loses its heat. False

• Thermal convection happens in liquids and gases. True

• Thermal convection happens in solids. False

• Sea breeze is caused by thermal conduction. False

• Tea at the top of a cup is hotter than tea at the bottom of the same cup. True

   2. Convection currents in liquids and gases are the result of expansion caused by particles moving

       faster in hotter region.

   3. Hot-air balloon rises because the hot air inside it is less dense than the cool air surrounding it.