## Lakshya Education MCQs

Question: A solid cube just gets completely immersed in water when a 0.2 kg mass is placed on it. If the mass is removed, the cube is 2 cm above the water level. What is the length of each side of the cube?
Options:
 A. 12 cm B. 10 cm C. 8 cm D. 6 cm
: B

Option:(b)

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## More Questions on This Topic :

Question 1. Which one of the following reflects back more sunlight as compared to other three?
1.    Sand desert
3.    Land covered with fresh snow
4.    Prairie land
: C

Option:(C)
Question 2. A hollow sphere of radius R, a hollow cube of side R and a thin circular plate of radius R, made up of the same material, are all heated to 20° C above room temperature. When left to cool in the room, which of them will reach the room temperature first?
1.    Circular plate
2.    Cube
3.    Sphere
4.    All of them will reach the room temperature at the same time
: C

Option:(c)
Question 3. Indiscriminate disposal of used fluorescent electric lamps causes mercury pollution in the environment. Why is mercury uses in the manufacture of these lamps?
1.    A mercury coating on the inside of the lamp makes the light bright white
2.    When the lamp is switched on, the mercury in the lamp causes the emission of ultra-violet radiations
3.    When the lamp is switched on, it is the mercury which converts the ultra-violet energy into visible light
4.    None of the statements given above is correct about the use of mercury in the manufacture of fluorescent lamps
: B

Option:(b)
Question 4. Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water.
Reason (R): A light coming from the stick undergoes scattering from water molecules giving the stick a short and bent appearance.
Codes
1.    Both A and R are true and R is the correct explanation of A
2.    Both A and R are true but R is not a correct explanation of A
3.    A is true but R is false
4.    A is false but R is true
: C

Option:(c)
Question 5. Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece.
Reason (R) : The density of copper is more than that of glass.
Codes
1.    Both A and R are true and R is the correct explanation of A
2.    Both A and R are true but R is not a correct explanation of A
3.    A is true but R is false
4.    A is false but R is true
: B

Option:(b)
Question 6. Consider the following statements
1.Light of longer wavelength is scattered much more than the light of shorter wavelength.
2.The speed of visible light in water is 0.95 times the speed in vacuum.
3.Radio waves are produced by rapidly oscillating electrical currents.
4.To detect the overspeeding vehicles, police use the Doppler effect of reflected short radio waves.
Which of these statements are correct?
1.    1 and 2
2.    1 and 3
3.    2 and 4
4.    3 and 4