Maximum density of $H_2O$ is at temperature

A lead bullet at $27\,^oC$ just melts when stopped by an obstacle. Assuming that $25\%$ of heat is absorbed by the obstacle, then the velocity of the bullet at the time of striking is  ........ $m/s$ ( $M.P.$ of lead = $327\,^oC$, specific heat of lead $= 0.03\,cal/g\,^oC$, latent heat of fusion of lead $= 6\,cal/g$ and $J = 4.2\,joule/cal$ )

A lead bullet at $27\ ^oC$ just melts when stooped by an obstacle. Assuming that $25\%$ of heat is absorbed by the obstacle, then the velocity of the bullet at the time of striking  ....... $m/s$  ( $M.P.$ of lead $= 327\,^oC$ , specific heat of lead $= 0.03\,cal/g\,^oC$ , latent heat of fusion of lead $= 6\,cal/g$ and $J = 4.2\,joule/cal$ )

On a new scale of temperature (which is linear) and called the $W$ scale, the freezing and boiling points of water are $39\,^oW$ and $239\,^oW$ respectively. What will be the temperature on the new scale, corresponding to a temperature of $39\,^oC$ on the Celsius scale ? ............. $^\circ \mathrm{W}$

The rods of length $L_1$ and $L_2$ are made of materials whose coefficients of linear expansion are $\alpha _1$ and $\alpha _2$. If the difference between the two lengths is independent of temperatures

Steam at $100\,^oC$ is passed into $22\,g$ of water at $20\,^oC$  The mass of water that will be present when the water acquires a temperature of $90\,^oC$  (Latent heat of steam is $540\,cal/g$) is ......... $\mathrm{g}$