Which of the following compounds is chiral?

In the molecule ${\mathrm{CH}}_2\mathrm{CHBrCl}$, which of the two hydrogens on the methylene carbon is pro-$R$?

Which of the following molecules is chiral?

Which of the following compounds can exist as enantiomers?

How many chiral centers are present in the structure of $2_{-}\text{chlorobutane}$?

Which of the following molecules is achiral?

Which of the following compounds is chiral?

When a molecule is $\mathrm{chiral}$, how does its mirror image compare to the original molecule?