The average atomic mass of Boron: 10.431 amu
<h3>Further explanation
</h3>
Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.
So Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu
Mass atom X = mass isotope 1 . % + mass isotope 2.% + ...
The average atomic mass of boron :

The subatomic particle involved in chemical bonding is the electron. Electrons are the smallest of all subatomic particles and orbit the nucleus in discrete energy levels called shells. Electrons are negatively charged and the nucleus is positively charged due to the protons.
Answer:
294.87 gm CaCl_2
Explanation:
The computation of the mass of calcium chloride is shown below:
But before that following calculations need to be done
Number of moles of chlorine atom is
= 3.20 × 10^24 ÷ 6.022 × 10^23
= 5.314 moles
As we know that
1 mole CaCl_2 have the 2 moles of chlorine atoms
Now 5.341 mole chloride atoms would be
= 1 ÷ 2 × 5.314
= 2.657 moles
Now
Mass of CaCl_2 = Number of moles × molar mass of CaCl_2
= 2.657 moles × 110.98 g/mol
= 294.87 gm CaCl_2
It requires using a mole ratio.