What is the name given to the p. d. across a cell or battery

In the first law of thermodynamics, triangle e=q-w, what does q stand for

Which statement correctly describes the interaction between magnetic poles? north and south poles attract each other. north and south poles repel each other. two north poles will attract each other. two south poles will attract each other.

What explosion in the upper solar atmosphere releases about as much energy as millions of 100-megaton hydrogen bombs exploding simultaneously?