The temperature of 1 mole of a liquid is raised by heating it with 750 joules of energy. It expands and does 200 Joules of work, calculate the change in internal energy of the liquid.

I want to use the expression: $$\Delta U = \Delta Q + \Delta W$$ so that: $$\Delta U = 750\,\mathrm J- 200\,\mathrm J = 550\,\mathrm J$$

but it strikes me that it can't be that simple (first year college exam paper). Also, of what significance is the '1 mole' of liquid?

The temperature of 1 mole of a liquid is raised by heating it with 750 joules of energy. It expands and does 200 joules of work, calculate the change in internal energy of the liquid.

I want to use the expression: $$\Delta U = \Delta Q + \Delta W$$ so that: $$\Delta U = 750\,\mathrm J- 200\,\mathrm J = 550\,\mathrm J$$

but it strikes me that it can't be that simple (first year college exam paper). Also, of what significance is the '1 mole' of liquid?