Strontium and barium have similar chemical properties because atoms of these elements have the same number of 1.protons
2.neutrons
3.electron shells
4. Valence electrons

4. Valence electrons

Explanation:

Strontium and barium have similar chemical properties because atoms of these elements have the same number of valence electrons.

The valence electrons are the outer shell electrons within an atom. Both strontium and barium belongs to the group of alkali -earth metals on the periodic table.

This group consists of elements with two valence electrons.

The number of valence electrons determines chemical properties.

air quality

poor drinking water

and heavy polution

can lead to poor health

answer

i think the answer is a) as air pressure in an area increases, the density of the gas particles in that area decreases.

hope it