Easy MCQ +4 / -1 PYQ · JEE Mains 2020

The radius R of a nucleus of mass number A can be estimated by the formula
R = (1.3 $\times$ 10–15)A1/3 m.
It follows that the mass density of a nucleus is of the order of :

(Mprot. $\cong$ Mneut $\simeq$ 1.67 $\times$ 10–27 kg)

  1. A 10<sup>24</sup> kg m<sup>–3</sup>
  2. B 10<sup>10</sup> kg m<sup>–3</sup>
  3. C 10<sup>17</sup> kg m<sup>–3</sup> Correct answer
  4. D 10<sup>3</sup> kg m<sup>–3</sup>

Solution

$R = (1.3 \times {10^{ - 15}}){A^{{1 \over 3}}}$<br><br>We know, $m = pV$<br><br>$\Rightarrow$ $p = {m \over V}$<br><br>$\Rightarrow$ $p = {{{m_p}A} \over {{4 \over 3}\pi {R^3}}}$<br><br>$p = {{{m_p}A} \over {{4 \over 3}\pi \times {{(1.3 \times {{10}^{ - 15}})}^3}A}}$<br><br>$p \approx {10^{17}}kg/m$

About this question

Subject: Physics · Chapter: Atoms and Nuclei · Topic: Nuclear Binding Energy

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