In which orbital does an electron in a bromine atom experience the greatest effective nuclear charge?

Explanation:

As the shielding effect is the effect which occurs when electrons shield each other from being attracted by the nucleus.

The effective nuclear charge is the net effective positive charge experienced by the electrons in an atom.

The electronic configuration of bromine is as follows.

Since, 1s orbital is closure to the nucleus hence it will experience the greatest nuclear charge.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.