Which of the following does not follow the first law of thermodynamics? $(W = \text{work}, Q = \text{heat}, \Delta U = \text{change in internal energy})$

During the melting of a slab of ice at $273 \ K$ at atmospheric pressure,

The first law of thermodynamics is concerned with the conservation of

$A$ given quantity of gas is taken from $A$ to $C$ in two ways: $a$) directly from $A \rightarrow C$ along a straight line, and $b$) in two steps, from $A \rightarrow B$ and then from $B \rightarrow C$. The work done and heat absorbed along the direct path $A \rightarrow C$ are $200 \ J$ and $280 \ J$ respectively. If the work done along the path $A \rightarrow B \rightarrow C$ is $80 \ J$, find the heat absorbed along this path.

$7$ mole of a certain monoatomic ideal gas undergoes a temperature increase of $40 K$ at constant pressure. The increase in the internal energy of the gas in this process is $.... J$ (Given $R = 8.3 J K^{-1} mol^{-1}$)

$A$ monoatomic gas of $n$ moles is heated from temperature $T_1$ to $T_2$ under two different conditions: $(i)$ at constant volume and $(ii)$ at constant pressure. The change in internal energy of the gas is