A rectangular vessel with linear expansion coefficient \( \alpha=2 \times 10^{-4} /{ }^{\circ} C \) has a liquid with volume expansion coefficient \( \gamma_{\text {liquid }}=3 \times 10^{-3} /{ }^{\circ} C \) and density \( 2 g / cc \) upto a height of \( 50 cm \). If the temperature increases by \( 20^{\circ} C \), change of pressure at the base of the vessel will be
(1) \( 80 N / m ^{2} \)
(2) \( 100 N / m ^{2} \)
(3) \( 60 N / m ^{2} \)
(4) \( 75 N / m ^{2} \)
