In a circuit of two lamps in parallel there is 5 v across one lamp. what is the voltage across the other lamp? answer in units of v.

The voltage across the other lamp is also 5 V.
In fact, when two resistances are connected in parallel, they are connected to the same points of the circuit. This also means that the potential difference across the two sides of the resistors is the same, therefore the voltage across the two lamps connected in parallel is 5 V for both.