Question

If 0.5 g of any substance is completely transformed into energy, then how much energy in kilo-joule will be obtained ?

• A. $1.5\times {10}^{10}$ kilo-joule
• B. $3.0\times {10}^{10}$ kilo-joule
• C. $4.5\times {10}^{10}$ kilo-joule
• D. $6.0\times {10}^{10}$ kilo-joule

Answer 1

The correct option is C $4.5\times {10}^{10}$ kilo-joule

m =0.5 g = $5\times {10}^{-4}$kg
c = $3\times {10}^8$m/s
From Einstein's mass-energy equivalence relation,
$E=m{c}^2$
E = $5\times {10}^{-4}\times (3\times {10}^8{)}^2$J
= $45\times {10}^{12}$J
= $4.5\times {10}^{10}$ kilo-joule
Hence, option C is the correct answer.