Matter in a neutron star has about the same density as nuclear matter, \(2.3\times10^{17}\ \mathrm{kg\,m^{-3}}\). The mass of \(1\ \mathrm{mm^{3}}\) of such matter is about
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(2.3\times10^{8}\ \mathrm{kg}\)
Mass is density times volume. Since \( 1\ \mathrm{mm}=10^{-3}\ \mathrm{m} \), the volume is \( 1\ \mathrm{mm^{3}}=10^{-9}\ \mathrm{m^{3}} \).
\( \begin{aligned} m &= \rho V \\ &= 2.3\times10^{17}\times10^{-9} \\ &= 2.3\times10^{8}\ \mathrm{kg} \end{aligned} \)
From the above, just one cubic millimetre of this matter has a mass of about \( 2.3\times10^{8}\ \mathrm{kg} \).
NCERT (2026-27):
Size of the Nucleus – “… The density of nuclear matter is approximately 2.3 × 1017 kg m–3. …”
Example 13.1 – “The density of matter in neutron stars (an astrophysical object) is comparable to this density. …”