$A$ leaf which contains only green pigments is illuminated by a laser light of wavelength $0.6328 \,\mu m$. It would appear to be

Match Column-$1$ with Column-$2$ when a wave propagating in a denser medium enters a rarer medium:

Column-$1$	Column-$2$
$(a)$ Speed	$(i)$ Increases
$(b)$ Its amplitude	$(ii)$ Decreases
	$(iii)$ Remains constant

$A$ source of light emits a continuous stream of light energy which falls on a given area. Luminous intensity is defined as

Assertion : Different colours travel with different speed in vacuum.
Reason : Wavelength of light depends on refractive index of medium.

Assertion: The colour of the green flower seen through red glass appears to be dark.
Reason: Red glass transmits only red light.

The intensity of light from a continuously emitting laser source operating at $638 \,nm$ wavelength is modulated at $1 \,GHz$. The modulation is done by momentarily cutting the intensity off with a frequency of $1 \,GHz$. What is the farthest distance apart two detectors can be placed in the line of the laser light,so that they can see the portions of the same pulse simultaneously?
(Consider the speed of light in air $c = 3 \times 10^{8} \,m/s$)