Question

What is the nuclear binding energy for a mole of helium, He-5, whose atomic mass is 5.01222? (1 mol p⁺ = 1.00728 g, n⁰ = 1.00866 g, c=3.00x10⁸m s^-1, and 1 J=1 kg m² s^-2)

	2.72x1017J
	2.72x1014J
	2.55x1012J
	2.55x1015J

A radioisotope has a 30-second half-life. After one and a half minutes there will be

	50% left
	25% left
	12.5% left
	0% left

For a radioisotope whose half-life is 5 minutes, after two half-lives there is left

	nothing
	75% of the original sample
	25% of the original sample
	50% of the original sample

Answer 1

1st question : 2.55*10¹² J

2nd question : 12.5 %

3rd question : 25 %