631. Detergents dissolved in water help in cleaning clothes by
A. Increasing the temperature of water
B. Reacting chemically with dirt
C. Reducing the surface tension of water
D. None of these

632. The absorption of ink by blotting paper involves
A. Viscosity of ink
B. Capillary action phenomenon
C. Diffusion of ink through the blotting
D. None of these

633. Materials for rain-proof coats and tents owe their water proof properties to
A. Surface tension
B. Viscosity
C. Specific gravity
D. None of these

634. For being able to see three-dimensional pictures we have to use
A. A binocular
B. A camera
C. An epidiascope
D. None of these

635. Water has maximum density at
A. 0 C
B. 4 C
C. 4.8 C
D. None of these

636. The theory of Expanding Universe was first propounded by
A. Einstein
B. Newton

C. Gahleo
D. None of these

637. Water vapor beyond the dew point result in
A. Precipitation
B. Hailstorm
C. Condensation
D. None of these

638. The main chemical substance present in the bones and teeth of animals is
A. Sodium chloride
B. Sugar
C. Calcium Phosphate
D. None of these

639. The major component of honey is
A. Glucose
B. Sucrose
C. Maltose
D. None of these

640. The working principle of a washing machine is
A. Centrifugation
B. Dialysis
C. Reverse Osmosis
D. None of these