At room temperature, chlorine is a gas, bromine is a liquid, and
iodine is a solid. However, all
three elements share some
physical properties. They also
have very similar chemical
properties. They are grouped in the same column on the periodic table. What common property do
you observe?

Explanation:

One common property with all halogens in group 7 is that they are all non-metals.

Fluorine, chlorine, Bromine and Iodine are classified as non-metallic elements and they have a high electronegativity.

The most prominent observation from halogens is that they all non-metallic in nature.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me