Question

define relative atomic mass

Answer 1

Relative atomic mass: The R.A.M is of an element is the no. of times an element is heavier than an atom of Carbon-12 isotope.

Actually, the atomic mass we use is the relative atomic mass and not the actual mass of any element. Hence, if oxygen has an atomic mass 16 a.m.u it means its one atom is 16 times heavier than a C-12 atom.

it is taken because, Carbon -12 isotope has been assigned as the standard isotope.