1721. Permanent hardness of water is due to the presence of :

A. Calcium bicarbonate
B. Magnesium bicarbonate
C. Calcium Sulphate *
D. Sodium bicarbonate

1722. Laser is an acronym for :

A. Light amplification by standard emission of light
B. Light absorption stimulated entrance of radiation
C. Light amplification by stimulated emission of radiation *
D. Standard radiation emission’s absorption of light

1723. If carbon dioxide is passed through lime water for a long time , the cloudy white colour initially formed disappears because of the formation of :

A. Calcium bicarbonate *
B. Calcium hydroxide
C. Calcium carbonate
D. Calcium sulphate

1724. Articles made of copper and bronze slowly tarnish in air and turn green, the green colour is due to the formation of :

A. Copper oxide*
B. Copper sulphide
C. Copper oxalate
D. All of these

1725. Bleaching powder losses its power on keeping for a long time because :

A. It changes into calcium hypochlorite
B. It changes into calcium chloride and calcium hydroxide
C. It assimilates dampness
D. It changes into calcium chloride and calcium chlorate *

1726. When the quantity of charge on each of the two bodies is doubled , the force between them becomes :

A. One fourth
B. One half
C. Twice
D. Four times *

1727. Light year is related to :

A. Time
B. Distance *
C. Energy
D. Speed

1728. The word ceramic means :

A. Hard material
B. Soft material
C. Dry material
D. Burnt material *

1729. The operations of solar cell is based on :

A. Laser technology
B. Photoconduction *
C. Thermal emission
D. Tyndall effect

1730. The minimum number of bits required to store hexadecimal number AF is :

A. 2
B. 4
C. 8
D. 16