Statement A: Density of nucleus is independent of its mass numberStatement B: Beryllium is used as a moderator in nuclear reactorsA. Both A and B are correctB. Both A and B are wrongC. A is correct, B is wrongD. A is wrong, B is correct

A. Both A and B are correct.

Explanation:
Statement A: "Density of nucleus is independent of its mass number."
This statement is correct. The density of the nucleus, which is the central core of an atom, is approximately constant regardless of the mass number (number of protons and neutrons) of the nucleus. The density of the nucleus is incredibly high compared to the overall density of the atom since the majority of the atom's mass is concentrated in the tiny nucleus.

Statement B: "Beryllium is used as a moderator in nuclear reactors."
This statement is also correct. Beryllium is used as a moderator in certain types of nuclear reactors. A moderator's role is to slow down neutrons, which increases the probability of nuclear fission reactions. In some nuclear reactors, beryllium serves as a neutron moderator due to its ability to slow down fast neutrons effectively.

Therefore, option A is the correct answer.




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