set 15 MCQ Questions & Answers Detailed Explanation

Answer: (d)

Answer: (c)

Heat required by ice to raise its temperature to 100°C,

$Q_1 = m_1L_1 + m_1c_ 1Δϴ_1$ = 5 × 80 + 5 × 1 × 100 = 400 + 500 = 900 cal.

Heat given by steam when condensed,

$Q_2 = m_2L_2$ = 5 × 536 = 2680 cal as $Q_2 > Q_1$.

This means that whole steam is not even condensed.

Hence temperature of mixture will remain at 100°C.

Answer: (d)

The reason CDs reflect rainbow colours is because they have a clear plastic coating on top of a mirrored surface. Light refracts (bends) when it moves from one medium (such as air) to another with a different optical density (such as the clear plastic surface of a CD).

Different wavelengths of light (every colour has a different wavelength) travel at different speeds so that the full spectrum appears when white light passes from the air through the plastic surface of a CD, separated light rays which are then reflected back to us by the mirrored centre surface of a CD.

Here the diffraction and transmission also take place because diffraction of light rays occurs when it strikes the surface of CD and transmission is obvious when light enters from one medium to another.

The thickness of the different optical media, angle of source light, and brightness of source light all affect which rainbow patterns are visible on a CD.

Answer: (d)

Answer: (c)

Answer: (b)