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) When a wave travels from a denser medium to a rarer medium:
$1$. The speed of the wave increases because the refractive index of the rarer medium is lower,and the wave encounters less resistance ($v = f \lambda$,and since frequency $f$ remains constant,speed $v$ increases as wavelength $\lambda$ increases).
$2$. The amplitude of the transmitted wave decreases because part of the wave energy is reflected back at the interface between the two media.
Therefore,the correct matching is: $(a-i), (b-ii)$.