Correct Answer - C
If atomic mass of x=a, then that of y=2a
`therefore` Eq. mass `=("at. Mass")/("valency")`
`therefore` Eq. mass of `x=a//3`. Eq mass of
`y=2a//2=a`.
`("Mass of x")/("Mass of y")=("Eq. mass of x")/("E q mass of y")`
`=(a//3)/(1)=(1)/(3)= 1:3`