NEET Physics — Thermal Properties of Matter

How much heat is needed to convert \( 0.1 \, \text{kg} \) of mercury at \( -39^\circ \text{C} \) to liquid at \( 357^\circ \text{C} \)? (Specific heat of solid mercury = \( 140 \, \text{J kg}^{-1} \text{K}^{-1} \), latent heat of fusion = \( 0.12 \times 10^5 \, \text{J kg}^{-1} \), specific heat of liquid mercury = \( 140 \, \text{J kg}^{-1} \text{K}^{-1} \))

A copper rod of length \( 80 \, \text{cm} \) at \( 40^\circ \text{C} \) is cooled until its length decreases by \( 0.0136 \, \text{cm} \). What is the final temperature? (\( \alpha_l = 1.7 \times 10^{-5} \, \text{K}^{-1} \))

A \( 0.15 \, \text{kg} \) mercury block at \( 400^\circ \text{C} \) is placed in \( 0.5 \, \text{kg} \) water at \( 20^\circ \text{C} \) in a \( 0.05 \, \text{kg} \) aluminium calorimeter at \( 20^\circ \text{C} \). Find the final temperature. (Specific heat of mercury = \( 140 \, \text{J kg}^{-1} \text{K}^{-1} \), water = \( 4186 \, \text{J kg}^{-1} \text{K}^{-1} \), aluminium = \( 900 \, \text{J kg}^{-1} \text{K}^{-1} \))

During the melting of ice at \( 0^\circ \text{C} \), why does the temperature remain constant despite heat being supplied?

Which temperature scale uses absolute zero as its starting point?