Correct Answer - B::C
H=30 cm
n=3/2
`H_(1)=H//nimplies (30xx2)/3=20 cm`
Case-II :
R=300cm
`(n_(2))/v-(n_(1))/u=(n_(2)-n_(1))/R`
`1/(-H_(2))-3/(-2xx30)=(1-3/2)/(-300)`
`H_(2)=600/29=20.684 cm `
Case -III
`(n_(2))/v-(n_(1))/u=(n_(2)-n_(1))/R, " " 1/(-H_(3))-3/(-2xx30)=(1-3/2)/300, H_(3) =600/31 =19.354 cm `