Which one of the following is always not negative?

The heat evolved during the combination of $24 \, g$ of $C$ and $128 \, g$ of $S$ according to the reaction $C + 2S \to CS_2$ with $\Delta H = 22.0 \, kcal$ is:

For a reaction,$X_{2(g)} + Y_{2(g)} \rightleftharpoons 2XY_{(g)}$. If $\Delta G_r^o = 20 \ kJ \ mol^{-1}$ and $\Delta S_r^o = -20 \ J \ K^{-1} \ mol^{-1}$ at $200 \ K$. Calculate $\Delta H_r^o$ at $400 \ K$ (Given $\Delta_r C_P = 20 \ J \ K^{-1} \ mol^{-1}$).

For the reaction at $300 \, K$,$A_{(g)} + B_{(g)} \to C_{(g)}$,given $\Delta U = -3 \, kcal$ and $\Delta S = -10 \, cal/K$. The value of $\Delta G$ will be $...... \, cal$.

$C_{(graphite)} + O_{2(g)} \to CO_{2(g)}; \Delta H = - 94.05 \ k \ cal \ mol^{-1}$
$C_{(diamond)} + O_{2(g)} \to CO_{2(g)}; \Delta H = - 94.50 \ k \ cal \ mol^{-1}$
Therefore:

If $100$ mole of $H_2O_2$ decomposes at $1$ bar and $300$ $K$,the work done $(kJ)$ by $50$ mole of $O_{2(g)}$ as it expands against $1$ bar pressure is............. $kJ$
$2H_2O_{2(l)} \rightleftharpoons 2H_2O_{(l)} + O_{2(g)}$
$(R = 8.3 \ J \ K^{-1} \ mol^{-1})$