Question

$Li$ nucleus has three protons and four neutrons. Mass of lithium nucleus is $7.016005 \,amu$. Mass of proton is $1.007277 \,amu$ and mass of neutronis $1.008665\, amu$. Mass defect for lithium nucleus in $amu$ is

• A. 0.04048 amu
• B. 0.04050 amu
• C. 0.04052 amu
• D. 0.04055 amu

Answer 1

Answer: (B)

Mass defect $=$ mass of nucleons $-$ mass of nucleus
$=(3 \times 1.007277+4 \times 1.008665)-7.016005$
$=0.040486$ amu
$\approx 0.04050$ amu