The stars twinkle because:
- (A) Of the presence of strong winds
- (B) They stop and then start shining occasionally
- (C) Of the disturbance in the atmosphere of different densities
- (D) They are a conglomeration of many stars which shine but one at a time
- (C) Of the disturbance in the atmosphere of different densities
The police use the dogs for detective work because:
- (A) They can run very fast
- (B) They are easily trainable
- (C) They have sharp eyesight
- (D) They can hear ultrasonic waves
- (D) They can hear ultrasonic waves
Why is the light of an ordinary lamp hotter than the tube light?
- (A) It gives white light
- (B) It is due to incandescence
- (C) It has more surface for distribution of energy
- (D) It is due to ionization of gases
- (B) It is due to incandescence
Water is highly effective coolant for a car engine because:
- (A) Water is a bad conductor of heat
- (B) Water is a good conductor of heat
- (C) Water has very high specific heat capacity
- (D) Evaporation of water produces lot of cooling
- (C) Water has very high specific heat capacity
A greenish yellow color is seen on a boiled egg. This is due to:
- (A) Formation of some iron compounds
- (B) Oxidation of sulphur in the egg
- (C) Oxidation of some vitamins in the egg
- (D) Oxidation of phosphorus in the egg
- (A) Formation of some iron compounds
A fresh egg sinks in pure water whereas it floats in saturated salty water. This is because:
- (A) Of higher density of pure water
- (B) Of higher density of salty water
- (C) The fluid matter inside the egg has the same density as the salty water
- (D) Egg shell is made of calcium which is heavier than pure water
- (B) Of higher density of salty water
Why are two blankets warmer than one?
- (A) Two blankets have more wool hence provide greater warmth
- (B) Two blankets enclose air which does not allow the cold to perpetrate
- (C) Two blankets compress the air in between the body and this compression produces heat
- (D) Two blankets have great specific heat capacity
- (B) Two blankets enclose air which does not allow the cold to perpetrate
The blue color of the water in the sea is due to:
- (A) Absorption of other colors by water molecules
- (B) Reflection of the blue light by the impurities in sea water
- (C) Reflection of blue sky by seawater and scattering of blue light by water molecules
- (D) Polarization and dispersion of light by water molecules
- (C) Reflection of blue sky by seawater and scattering of blue light by water molecules
Microwave links are preferred for telephone because:
- (A) Reception is cheaper
- (B) Transmission easier
- (C) More telephones can be used
- (D) Long-distance telephone becomes easier
- (D) Long-distance telephone becomes easier
Clear nights are colder than cloudy nights because of:
- (A) Radiation
- (B) Conduction
- (C) Insolation
- (D) Condensation
- (A) Radiation