1471. Which on of the following is an air pollution gas and is released by burning of fossil fuel?

A. Nitrogen
B. Hydrogen
C. Oxygen
D. Sulphur dioxide *

1472. Who is credited with the discovery of nylon ?

A. Frederick Banting
B. Jonas Salk
C. Wallace caroches *
D. Linus pauling

1473. What is the main constituent of a pearl?

A. Calcium carbonate onlY
B. Calcium sulphate only
C. Calcium oxide and calcium sulphate
D. Calcium carbonate and magnesium carbonate *

1474. Gypsum is added to clinker during cement manufacturing to :

A. A decrease the rate of setting of cement *
B. Bind the particles of calcium silicate
C. Faciliatate the formation of colloidal gelD
D. Impart strenght to cement

1475. Which one among the following elements/ions is essential in small quantities for development of healthy teeth butt causes mottling of the teeth if consumed in higher quantities ?

A. Flouride *
B. Chloride
C. Iron
D. Potassium

1476. Contact lenses are made from :

A. Polyvinyl chloride *
B. Teflon
C. Polystyrene
D. Lucite

1477. Which one among the following metals is used for making boats because it does no corrode by sea water ?

A. Nickel *
B. Tungsten
C. Antimony
D. Titanium

1478. Which one among the following is a strong smelling agent added to LPG cylinder to help in the detection of gas leakage ?

A. Thioethanol *
B. Ethanol
C. Methane
D. Chloroform

1479. Which one among the following substances evolves heat when dissolved in water ?

A. Potassium nitrate
B. Glucose
C. Sodium chloride
D. Calcium oxide *

1480. Dead organs are generally stored in formalin formalin is :

A. Aqueous formaldehyde *
B. Aqueous ferrous sulphate
C. Aqueous formic acid
D. Aqueous ferric alum