Why is water used as a coolant in automobile radiators?

Which of the following is the unit of specific heat?

$A$ lead bullet of mass $10 \ g$ travelling at $300 \ m/s$ strikes against a block of wood and comes to rest. Assuming $50\%$ of heat is absorbed by the bullet, the increase in its temperature is (Specific heat of lead $= 150 \ J/kg \cdot ^{\circ}C$) (in $^{\circ}C$)

Two substances $A$ and $B$ of the same mass are heated at a constant rate. The variation of temperature $\theta$ of the substances with time $t$ is shown in the figure. Choose the correct statement.

The amount of heat required to raise the temperature of a body by $1^oC$ is called its

Is the molar specific heat of a solid a constant value? Explain.