The coefficient of apparent expansion of mercury in a glass vessel is 153 x 10- 6 /0C  and in a steel vessel is 144 x 10- 6/°C. If α for steel is 12 x 10-6/°C, then that of glass is

We know thatγreal =γapparent +γvessel So,γapp +γvessel glass =γapp +γvessel steel ∵γreal  is same in both cases) Or 153×10−6+γvessel glass =144×10−6+γvessel steel  Further γvessel steel =3α=3×12×10−6=36×10−6/∘C∴ 153×10−6+γvessel glass =144×10−6+36×10−6Solving, we getγvessel glass =27×10−6/∘Cor    α=γgalss 3=9×10−6/∘C