The answer is: 8.14·10⁶³ moles of lithium are present.
N(Li₂SO₄) = 2.45·10⁸⁷; number of formula units of lithium sulfate.
n(Li₂SO₄) = N(Li₂SO₄) ÷ Na.
n(Li₂SO₄) = 2.45·10⁸⁷ ÷ 6.022·10²³ 1/mol.
n(Li₂SO₄) = 4.07·10⁶³ mol; amount of lithium sulfate
In one molecule of lithium sulfate, there are two atoms of lithium.
n(Li₂SO₄) : n(Li) = 1 : 2.
n(Li) = 2 · 4.07·10⁶³ mol.
n(Li) = 8.14·10⁶³ mol; amount of lithium atoms.
