The density of water at 20°C is 998 kg/m3 and at 40°C is 992 kg/m3. The coefficient of volume expansion of water is

$As ρ_{T_{2}} = \frac{ρ_{T_{1}}}{(1 + γ Δ T)} = \frac{ρ_{T_{1}}}{1 + γ (T_{2} - T_{1})}$

$Here, T_{1} = 20 ° C, T_{2} = 40 ° C$

$ρ_{20} = 998 kg / m^{3}, ρ_{40} = 992 kg / m^{3}$

$∴ 992 = \frac{998}{1 + γ (40 - 20)} 992 = \frac{998}{1 + 20 γ}$

$992 (1 + 20 γ) = 998$

$1 + 20 γ = \frac{998}{992} or 20 γ = \frac{998}{992} - 1 = \frac{6}{992}$

$γ = \frac{6}{992} \times \frac{1}{20} = 3 \times 10^{- 4} / {}^{\circ}C$

The density of water at $20 ° C is 998 kg / m^{3}$ and at $40 ° C i s 992 k g / m^{3}$ . The coefficient of volume expansion of water is