science 2c

You feel ........... when you rub your hands.

• Cold

• Warm

You.................see electricity while traveling through wires.

• Can't

• Can

................. help on burning.

• Carbon dioxide

• Oxygen

Air consists of oxygen and............... and other gases.

• Nitrogen

• Water

Oxygen is...........% of air.

• 21

• 78

Oxygen is............. than air.

• Heavier

• Lighter

Carbon dioxide is................

• Colorful

• Colorless

Knocking on the door is .......

• Heat energy

• Sound energy

The main source of heat is............

• Sun

• Moon

Electricity travels through...........

• Air

• Electric wire