1. How many molecules are in 4.5 moles?

2.4 ⋅ 10 24

Explanation:

All that you need to know here is that in order for a given sample of water to contain exactly  1  mole of water, it must contain  6.022 ⋅ 10 23  molecules of water.

This is known as Avogadro's constant and essentially acts as the definition of a mole. If you have  6.022 ⋅ 10 23  molecules of water, then you can say for a fact that you have  1  mole of water.

a electronegativity decreases beacuse the size of nucleus is bigger.