How many valence electrons does each Cholrine atom have?

Hydrogen and helium are both members of?

How will the system respond to a temperature increase?

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water