Is the splitting of water an exothermic or an endothermic process?

$A$ thermodynamic system is taken from an initial state $i$ with internal energy $U_i = 100 \ J$ to the final state $f$ along two different paths $iaf$ and $ibf$,as schematically shown in the figure. The work done by the system along the paths $ia$,$af$,$ib$ and $bf$ are $W_{ia} = 50 \ J$,$W_{af} = 200 \ J$,$W_{ib} = 50 \ J$ and $W_{bf} = 100 \ J$ respectively. The heat supplied to the system along the paths $iaf$ and $ibf$ are $Q_{iaf}$ and $Q_{ibf}$ respectively. If the internal energy of the system in the state $b$ is $U_b = 200 \ J$ and $Q_{iaf} = 500 \ J$,the ratio $Q_{ibf} / Q_{iaf}$ is:

One mole of a gas expands such that its volume $V$ changes with absolute temperature $T$ in accordance with the relation $V = K T^2$,where $K$ is a constant. If the temperature of the gas changes by $60 \text{ K}$,then the work done by the gas is ($R$ is the universal gas constant).

One mole of an ideal gas undergoes a cyclic process,consisting of two isochores and two isobars. Temperatures at points $1$ and $3$ are $T_1$ and $T_3$ respectively. Find the work done by the gas over the cycle,if points $2$ and $4$ lie on the same isotherm.

When heat $Q$ is supplied to a monoatomic gas at constant pressure,the work done by the gas is:

Given $P_A = 3 \times 10^4 \, Pa$,$P_B = 8 \times 10^4 \, Pa$,$V_A = 2 \times 10^{-3} \, m^3$,and $V_D = 5 \times 10^{-3} \, m^3$. An ideal gas absorbs $600 \, J$ of heat in the process $AB$ and $200 \, J$ of heat in the process $BC$. Find the change in internal energy between $A$ and $C$ in $J$.