Sound waves must travel through a .....

When light hits a ..... surface, it reflects in all directions.

Light cannot pass through objects that are ....

..... changes the state of matter.

..... is when a liquid changes to a gas

Sound travels faster through air than through water.

A mirror is an example of ...

Natural light sources …

Light travels at about ...

Space is a giant, empty vacuum with air.

Light changes direction when it passes through a medium with different density.

How a hot-air balloon works in an example of ...

Geothermal energy is ...

The higher the temperature, the ... the molecules move.

Tick all the thermal insulators that do not conduct heat well

Ice cubes and butter melt when they are heated

We perceive large vibrations as ...

The moon is a natural light source

It has natural and artificial sources