101. In which of the following conditions wet clothes will dry earliest?
1. 100% RH, 60°C temperature
2. 100% RH, 20°C temperature
3. 20% RH, 20°C temperature
4. 20% RH, 40°C temperature
Option “4” is correct. The wet clothes will dry earliest at minimum humidity & maximum temperature. Thus according to options given in question, option (d) will dry the wet clothes earliest.
102. In the night wind blows fast, dew is not formed because-
1. Rate of evaporation is fast
2. Moisture in air is low
3. Temperature is high
4. Sky is not clear
Option “1” is correct. Dew is not formed on the night of strong wind as due to strong wind the rate of evaporation is fast. Thus, the particles of the dew tend to evaporate.
103. When beams of red, blue and green lights fall on the same spot, the colour of the light becomes:
1. Violet
2. Red
3. Yellow
4. White
Option “4” is correct. Red, green and blue are referred to as the primary colours of light. If we add the pair of primary colours we obtain white colour.
104. What is the distance between two successive crests or successive troughs called?
1. Amplitude
2. Wavelength
3. Frequency
4. None of these
Option “2” is correct. The distance between two successive crests or two successive troughs is the wavelength for a transverse wave.
105. Diffusion of light in the atmosphere takes place due to:
Option “2” is correct. Sunlight is the mixture of different colours. When it passes through the atmosphere it is scattered by the air molecules, particles of dust and other subtle materials which are present in the pathway.
106. When a mirror is rotated by an angle θ, the reflected ray will rotate by:
1. 0
2. θ/2
3. θ
4. 2θ
Option “4” is correct. If a plane mirror is rotated through a certain angle, then the reflected ray rotates through twice of that angle. So if a mirror is rotated by an angle θ, the reflected ray will rotate by 2θ.
107. Force of attraction between the molecules of different substances is called-
1. Surface tension
2. Cohesive force
3. Adhesive force
4. None of above
Option “3” is correct. Adhesive forces are the attractive forces between unlike molecules.
108. The speed of light will be minimum while passing through-
1. Glass
2. Vacuum
3. Water
4. Air
Option “1” is correct. Any of the object or material which has the highest refractive index has the minimum speed of light. The glass has the highest refractive index among other like, vacuum, water and air.
109. The radius of curvature of the plane mirror is:
1. Zero
2. One
3. Infinity
4. Between one and infinity
Option “3” is correct. The radius of curvature of plane is infinity.
110. Which one of the following is the best conductor of electricity?
1. Mica
2. Copper
3. Gold
4. Silver
Option “4” is correct. Electrical conductivity is a measure of the amount of electrical current under a material can carry. The most electrically conductive element is silver.
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