
If C(diamond) \(\rightarrow\) C(graphite) + \(X\text{kJ mol}^{-1}\)
C(diamond) +\( O_2(g)\) \(\rightarrow\) \(CO_2(g) + Y\text{kJ mol}^{-1} \)
C(graphite) + \(O_2(g)\) \(\rightarrow\) \(CO_2(g) + Z\text{kJ mol}^{-1}\)
at constant temperature, then
Two balls made of the same material collide perfectly inelastically as shown. The energy lost in the collision is completely utilized in raising the temperature of each ball. Find the rise in temperature of the balls. (Specific heat $=31$ cal/kg-$^\circ$C): 
$A$ and $B$ are identical point masses. $A$ is released as shown in the diagram at an angle $60^\circ$ from the vertical. Find $R$ if $B$ is able to reach point $C$ after elastic impact. 
