The addition of electron shells results in from the nucleus.
shielding of electrons
Answer here

shielding of electrons

Explanation:

The addition of electrons shells results in the shielding of electrons away from the nucleus, most importantly the nuclear pull resulting from the charge.

The effect is responsible for a wide range of properties of elements.

answer: the rock sample is a sedimentary rock.

explanation:

it is given that:

mass of rock sample, m = 2.7 g

volume of rock sample,

so, density of rock sample will be

since, the density of rock sample is . hence, the rock sample is a sedimentary rock, whose densities varies between .