Two protons exert a nuclear force on each other. The distance between them is of the order of
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 10^{-15}\,\mathrm{m} \)
The nuclear force is a short-range force. Two protons feel it only when they are within a few femtometres of each other. Since \( 1\,\mathrm{fm}=10^{-15}\,\mathrm{m} \), their separation is of the order of \( 10^{-15}\,\mathrm{m} \), the size of a nucleus.
NCERT (2026-27):
Nuclear Force – “(ii) The nuclear force between two nucleons falls rapidly to zero as their distance is more than a few femtometres. This leads to saturation of forces in a medium or a large-sized nucleus, which is the reason for the constancy of the binding energy per nucleon.”
Size of the Nucleus – “It has been found that a nucleus of mass number A has a radius
\( R=R_0A^{1/3} \qquad (13.5) \)
where R0 = 1.2 × 10–15 m (=1.2 fm; 1 fm = 10–15 m).”