The atomic mass of one carbon 12 atom = 12 g/mol
Relative atomic mass [tex](A_{r})[/tex] of an element is the mass of one of its atoms relative to 1/12 the mass of one atom of carbon-12.
Relative atomic mass [tex](A_{r})[/tex] is given by the formula
[tex](A_{r})[/tex] = (Average mass of an atom ×12)/(mass of one atom of carbon-12)
From the question, x is twice heavier as one carbon 12 atom
∴ mass of x = 2 × 12 g/mol
mass of x = 24 g/mol
Then, the relative atomic mass of elements x is calculated thus
[tex]A_{r}= \frac{24gmol^{-1} \times 12}{12 gmol^{-1} }[/tex]
[tex]A_{r} = 24 \\[/tex]
Hence, the relative atomic mass of elements x is 24.
(NOTE: Relative atomic mass is unitless)
Learn more on relative atomic mass here: https://brainly.com/question/16824270
