Which of the following is the correct mathematical expression for the first law of thermodynamics?

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

$A$ mixture of $2 \ mol$ of carbon monoxide and $1 \ mol$ of oxygen in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If $\Delta H$ is the enthalpy change and $\Delta E$ is the change in internal energy,then:

For an isothermal reversible expansion process,the value of $q$ can be calculated by the expression

If a system absorbs $30 \ kJ$ of heat and performs $12 \ kJ$ of work on the surroundings,what is the increase in internal energy of the system (in $kJ$)?

The law of conservation of energy states that