# The lightest element in the periodic table is

$\begin{array}{1 1}(a)\;\text{Lithium}\\(b)\;\text{Fluorine}\\(c)\;\text{Hydrogen}\\(d)\;\text{Helium}\end{array}$

The lightest elements are at the beginning on the periodic table.
Hydrogen is the lightest and the most plentiful element in the universe.
Hydrogen mass no is 1
Hence (c) is the correct answer.
edited Nov 7, 2017