Question

which molecule is more polarizable?

Explanation:

Step1: Recall polarizability trend

Polarizability increases with larger atomic size and more electrons.

Step2: Compare F and Br

Bromine (Br) is larger and has more electrons than fluorine (F).

Step3: Analyze molecules

In $CF_4$ and $CBr_4$, the outer - atoms are F and Br respectively. Since Br is more polarizable than F, $CBr_4$ is more polarizable.

Answer:

The molecule $CBr_4$ (the one with Br atoms) is more polarizable.