During an isothermal process,which of the following is true?

When $1 \ mole$ of gas is heated at constant volume,the temperature rises from $273 \ K$ to $546 \ K$. If heat supplied to the gas is $x \ J$,then find the correct statement from the following.

Consider the same expansion,but this time against a constant external pressure of $1 \ atm$.

Consider the reaction at $298 \ K$:
$H_{2(g)} + Cl_{2(g)} \to 2HCl_{(g)}, \Delta H^o = -185 \ kJ$
What is $\Delta U^o$ for this reaction? .....$kJ$

$A$ gas can be taken from state $A$ to state $B$ via two different paths $ACB$ and $ADB$. When path $ACB$ is used, $60 \text{ J}$ of heat flows into the system and $30 \text{ J}$ of work is done by the system. If path $ADB$ is used, the work done by the system is $10 \text{ J}$. The heat flow into the system in path $ADB$ is: (in $text{ J}$)

For the reaction $CO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$ at constant temperature and pressure,which of the following statements is correct?