Zn(s)+Sn2+(aq)⇌Zn2+(aq)+Sn(s)
Given: F2.303RT=0.059V
Ecell0=2F2.303RTlogKc
⇒Ecell0=20.059log(1020)
⇒Ecell0=20.059×20
⇒Ecell0=0.59V
Ecell0=ESn2+/Sn0−EZn2+/Zn0
⇒Ecell0=ESn2+/Sn0−(−0.76)
⇒ESn2+/Sn0=−0.76+059=−0.17
⇒ESn/Sn2+0=0.17=17×10−2
So, answer is 17.