The mass of one atom of an element X is 2.0 × 10–23 g.

Calculate the atomic mass of element X.

What could element X be ?

#### Solution

**Given:**

Mass of an atom of element X = 2.0 × 10^{-23}g

We know that the mass of an atom of a substance is equal to the mass of 1 mole of that substance. 1 mole of a substance consists of 6.022 × 10^{23} atoms; therefore, the mass of an atom of a substance is equal to the mass of 6.022 × 10^{23} atoms.

Therefore, to calculate the atomic mass of element X, we need to calculate the mass of 6.022 × 10^{23} atoms of X.

Mass of 1 atom of X = 2.0 × 10^{-23}

Mass of 6.022 × 10^{23} atoms of X = 6.022 × 10^{23} × 2.0 × 10^{-23} = 12 u

Hence, the atomic mass of element X is 12 u.

Carbon has an atomic mass of 12 u; therefore, element X is carbon.