Although there exists a dipole moment in the molecule, I guess its nonpolar because the dipole is very small as the electronegativity difference between the Br and Cl is very low and so it can be neglected.
A warm front is also defined as the transition zone where a warmer air mass is replacing a cooler air mass
Dew point: The point at which air saturated with water vapor produces condensation which forms dew.
The answer is B photosynthesis
When a nucleus emits a positron, its atomic number is lowered by one but its mass number stays the same.