# The apparent expansion of a liquid when heated in a copper vessel is C and when heated in a silver vessel is S . If A is coefficient of linear expansion of silver is

$(a)\;\large\frac{C+S-3A}{3}\qquad(b)\;\large\frac{C+3A-S}{3}\qquad(c)\;\large\frac{C+3A+S}{3}\qquad(d)\;\large\frac{C+3S+A}{3}$

Answer : $\;\large\frac{C+3A-S}{3}$
Explanation :
$r_{real} = r_{app} + r_{container}$
$real = r_{app/cu} + r_{cu} = r_{app/si} +r_{S}$
$C + 3A = S + 3B$
$B = \large\frac{C + 3A -S}{3}\;.$