The coefficient of linear expansion of brass and steel rods are \(\alpha_1\) and \(\alpha_2\). Lengths of brass and steel rods are \(L_1\) and \(L_2\) respectively. If \((L_2-L_1)\) remains the same at all temperatures, which one of the following relations holds good?
1. \(\alpha_1L_2^2=\alpha_2L_1^2\)
2. \(\alpha_1^2L_2=\alpha_2^2L_1\)
3. \(\alpha_1L_1=\alpha_2L_2\)
4. \(\alpha_1L_2=\alpha_2L_1\)

The coefficient of area expansion \(\beta\) of a rectangular sheet of a solid in terms of the coefficient of linear expansion \(\alpha\) is:
1. \(2\alpha\)
2. \(\alpha\)
3. \(3\alpha\)
4. \(\alpha^2\)

A rod \(\mathrm{A}\) has a coefficient of thermal expansion \((\alpha_A)\) which is twice of that of rod \(\mathrm{B}\) \((\alpha_B)\). The two rods have length \(l_A,~l_B\) where \(l_A=2l_B\). If the two rods were joined end-to-end, the average coefficient of thermal expansion is:
1. \(\alpha_A\)
2. \(\frac{2\alpha_A}{6}\)
3. \(\frac{4\alpha_A}{6}\)
4. \(\frac{5\alpha_A}{6}\)

The temperature of water at the surface of a deep lake is \(2^{\circ} \mathrm{C}\). The temperature expected at the bottom is:
1. \(0^{\circ} \mathrm{C}\)
2. \(2^{\circ} \mathrm{C}\)
3. \(4^{\circ} \mathrm{C}\)
4. \(6^{\circ} \mathrm{C}\)