121.

Addition of excessive amounts of heat to a lake is referred to as

• greenhouse effect

• refrigeration effect

• heat bloom

• thermal pollution

Drug which helps to reduce anxiety and brings about calmness is

• tranquiliser

• diuretic

• analgesic

• antihistamine

Dry Ice is nothing but

• gaseous carbon dioxide

• washing soda

• solid carbon dioxide

• carbon monoxide

Which one of the following is obtained as slag in a blast furnace?

• Calcium Carbonate

• Calcium Sulphate

• Calcium Chloride

• Calcium Silicate

When H₂ gas is allowed to expand from a region of high pressure to a region of low pressure the temperature of the gas

• decrease to a small extent

• increases

• does not change

• decreases suddenly

Which of the following weeds has been found useful to check water pollution caused by industrial affluents?

• Parthenium

• Elephant grass

• Water hyacinth

• (a) and (b)

Drying oils contain a fairly large proportion of

• Saturated fatty acids

• Unsaturated fatty acids

• Fats

• Proteins

Pyroligneous acid obtained from wood contains

• 10% ethanol

• 10% formaldehyde

• 10% acetic acid

• 10% formic acid

Which of the following pairs is correctly matched?

• Gypsum-calcium hydroxide

• Milk of lime-sodium sulphate

• Glauber's salt-calcium sulphate

• Salt petre-potassium nitrate

We receive sunlight on earth surface. What type of light beams are these?

• Diverging

• Random

• Parallel

• Converging