Oxygen percentage in Earth is.......

• 21%

• 78%

• 1%

Manganese dioxide is.........

• Making oxidation

• Making combustion

• A catalyst

Iron rusting is an example for......

• Combustion

• Preparing oxygen in laboratory

• Oxidation

.................... is saving the oxygen percentage in Earth

• Oxygen tanks

• Photosynthesis process

• Respiration system

Photosynthesis needs

• Sun, oxygen, water

• Sun, carbon dioxide, water

• Sun, food, water

Oxygen can't help in burning

• True

• False

The atmosphere consists of

• Oxygen

• Carbon dioxide

• Nitrogen

• All of the above

The rapid combination between oxygen and the elements producing heat and light is called......

• burning

• respiration

• oxidation

The hydrogen peroxide is decomposed in the presence of manganese dioxide into .......

• water and hydrogen

• water and oxygen

• oxygen and hydrogen

.......gas does not burn ,but it helps in burning.

• Nitrogen

• Oxygen

• Carbon dioxide