Answer
a). (1) greater than ,
b). ratio = 1.32
Work Step by Step
n(Zircon) = 1.92
n(Fused Quartz) = 1.46
a). Speed of light is fused quartz will be (1) greater than that in Zircon. Speed of light in vacuum, speed of light in any medium and refractive index are related by :-
$n=\frac{c}{v}$
hence, as n increases v decreases
b). Now,
$\frac{v_{Q}}{v_{Z}}=\frac{c}{n_{Q}}\times\frac{n_{Z}}{c}=\frac{1.92}{1.46}=1.32$
