The rock cycle is a very slow process as the plates of the earth's crust are moving only a few:
Decimetres each years
Centimetres each years
Millimetres each years
Metres each years
Plant life developed in warm shallows seas. What did they release into the atmosphere after using carbon dioxide?
Oxygen
Hydrogen
Nitrogen
Water
Animal life came into existence, after the sufficient presence of:
Carbon
Energy
The boiling point of oxygen, nitrogen, argon and neon are -183o C , - 196oC and -246oC respectively. Which of these has lowest boiling points ?
Argon
Neon
The atmosphere of the earth is different from that of its neighbor because of the presence of:
Compounds
Gases
Chemicals
Life
The argon content in clean air.
0.1%
0.7%
0.9%
0.8%
Recycling plastics helps conserve the:
Petroleum
Metal ores
Non-metallic minerals
Fossil fuels
Which are not removed by water treatment?
Phosphate
Nitrate
Sulphate
Silicate
Plant and animal life continued to develop over millions of years until the earth reached its present balance of:
Natural cycles
Earth is sometimes referred to as blue marble due to the presence of:
Rock
Air
Plants