621. The rear view mirror of a motor vehicle is
A. Concave
B. Plane
C. Convex
D. None of these

622. Lead ball falls through water more slowly than through air because
A. The value of ‘g’ is less than water
B. Density of air is less than that of water
C. Of the viscous force in water
D. None of these

623. A Fahrenheit thermometer indicates temperature of 14°F. Its corresponding reading on the Celsius scale will be
A. -20C
B. -10C
C. +10C
D. None of these

624. Which one of the following sets of colour combinations is added in colour vision in TV?
A. Red, green and blue
B. Orange, black and violet
C. White , red and yellow
D. None of these-2

625. A train goes past a railway station at a high speed. A young boy standing on the edge of the platform is likely to
A. Remain unaffected
B. Fall away from the train
C. Fall toward the train
D. None of these

626. Select the arrangement of electromagnetic radiation which starts with the lowest energy and increases to greatest energy?
A. radio, visible, infrared, ultraviolet, x-ray, gamma ray
B. radio, infrared, visible, x-ray, gamma ray, ultraviolet
C. visible, radio, infrared, ultraviolet, x-ray, gamma ray
D. radio, infrared, visible, ultraviolet, x-ray, gamma ray

627. Water is a highly effective coolant for a car engine because
A. Water is good conductor of heat
B. Water has very high specific heat capacity
C. Evaporation of water produces lot of cooling
D. None of these

628. Scalding with steam is more severe than scalding by boiling water because
A. Steam can penetrate the skin
B. Steam is at a higher temperature
C. Steam contains more energy than boiling water
D. None of these

629. In order to prevent the corrosion of iron pipes they are often coated with a layer of zinc. This process is termed as
A. Electroplating
B. Annealing
C. Galvanization
D. None of these

630. The cracking sound heard when dry hair is combed with a hard rubber comb is due to
A. The hair barging against the charged comb
B. Small electric sparks
C. The rubbing of the comb with hair
D. None of these