REVISION!

The angel between the covalent bonds in water molecule is

• 100

• 104.5

• 105.4

• 145

Water is a ________ molecule

The bond formed between hydrogen and oxygen of the same water molecule is

• Hydrogen bond

• Ionic bond

• Covalent bond

• Weak bond

__________ is commercially known as Freon

• Nitrogen oxid

• Methane

• CFC

• Halons

Halons are used in

• Fire extinguisher

• Concord planes

• Freons

• Insecticides

The erosion of the ozone layer increases every

• September

• November

• February

• March

1.     From the harmful ultraviolet rays on humans __________________________

The layer the contains 75% of the atmospheric mass is

• Troposphere

• Ionosphere

• Stratosphere

• Mesosphere

The location between the stratosphere and mesosphere is

• Mesopause

• Stratopause

• Tropopause

• Exosphere

The increase in the average temperature of earth

• Global warming

• Green house effect