OXYGEN

What is percentage of oxygen in air?

• 21%

• 22%

• 23%

• 24%

Which gas helps in burning?

• Nitrogen

• Oxygen

• sulfur

• Carbon dioxide

The diver takes this gas cylinder with him to swim in a deep sea

• nitrogen

• oxygen

• Carbon dioxide

• ammonia

Which one of the following gas is used in acetylene torch for welding?

• Oxygen

• Hydrogen

• Carbon dioxide

• Neon

Without oxygen_______cannottakeplace in living things.

• respiration

• combustion

• phptosynthesis

• excretion

Oxygen is a_______ gas

• reactive

• nonreactive

• inert

• dangerous

Acetylene torch uses this gas for welding metals

• nitrogen

• oxygen

• neon

• argon

Oxygen does not burn but it helps in

• burning

• digestion

• photosynthesis

• excretion

oxygen reacts with metals and make their

• carbides

• oxides

• sulphites

• hydrites

The concentration of oxygen is higher in

• karachi

• islam Abad

• Lahore

• chitral