# A piece of metal weights 45 gms in air and 25 gms in a liquid of density $1.5 \times 10^3kg-m^{-3}$ kept at $30^{\circ}C.$ When the temperature of the liquid of density $1.5 \times 10^3\;kg-m^{-3}$ kept at $30^{\circ}C$. When the temperature of the liquid is raised to $40^{\circ}$, the metal piece weight 27 gms. The density of liquid at $40^{\circ}C$ is $1.25 \times 10^3\;kg-m^{-3}.$ The coefficient of linear expansion of metal is :

$\begin {array} {1 1} (1)\;1.3 \times 10^{-3}/ ^ {\circ}C & \quad (2)\;5.2 \times 10^{-3}/ ^{\circ}C \\ (3)\;2.6 \times 10^{-3}/ ^{\circ}C & \quad (4)\;0.26 \times 10^{-3} ^{\circ}C \end {array}$