Q: A nucleus with atomic number $ z $ and neutron number N undergoes two decay processes. The result is a nucleus with atomic number Z-3 and neutron number N-1. Which decay processes took place?

An $ \alpha- $ decay and a $ \beta^{+} $ decay. An alpha decay reduces the atomic number by 2 and the neutron number by 2, while a beta-plus decay converts a proton into a neutron, so Z decreases by 1 and N increases by 1. Combined, these give Z-3 and N-1, matching the result.

Q: Calculate the electrostatic potential energy at the instant when the alpha particle stops?

$ 36.3 \mathrm{MeV} $. When the alpha particle stops momentarily, its kinetic energy is zero, so the electrostatic potential energy equals the initial kinetic energy. Therefore the potential energy at that instant is 36.3 MeV.

Question 1

Assertion: The reaction; $ _{1} \boldsymbol{H}^{2}+_{0} \boldsymbol{n}^{1} \rightarrow $ $ _{2} H e^{4}+_{0} n^{1} $ will not happen Reason: The equation given is not balanced.

Accepted Answer

Assertion is false but Reason is true E. Both Assertion and Reason are false. The given nuclear equation is not balanced: the left side has mass number 3 and atomic number 1, while the right side has mass number 5 and atomic number 2. So the reason is true. However, the assertion is false because the reaction as written cannot be rejected for the stated reason alone; the equation itself is simply incorrect/unbalanced.

Question 2

Find out the missing particle in the following nuclear reaction? $ _{1}^{2} \boldsymbol{H}+_{29}^{63} \boldsymbol{C u} \rightarrow_{30}^{64} \boldsymbol{Z} \boldsymbol{n}+(?) $

Accepted Answer

Neutron. Balance the reaction by comparing total mass numbers and atomic numbers. The left side has mass number 65 and charge 30; since zinc-64 on the right has charge 30, the missing particle must have mass number 1 and charge 0, which is a neutron.

Question 3

The missing particle in the reaction: $ \underset{99}{253} \boldsymbol{E} \boldsymbol{s}+_{2}^{4} \boldsymbol{H} \boldsymbol{e} \rightarrow_{101}^{256} \boldsymbol{M} \boldsymbol{d}+ $

Accepted Answer

deuteron. The total mass number goes from 253 + 4 to 256, so the missing particle must have mass number 1. The atomic number goes from 99 + 2 to 101, so the missing particle must also have charge 0, which matches a neutron.

Question 4

A nucleus with atomic number $ z $ and neutron number N undergoes two decay processes. The result is a nucleus with atomic number Z-3 and neutron number N-1. Which decay processes took place?

Accepted Answer

An $ \alpha- $ decay and a $ \beta^{+} $ decay. An alpha decay reduces the atomic number by 2 and the neutron number by 2, while a beta-plus decay converts a proton into a neutron, so Z decreases by 1 and N increases by 1. Combined, these give Z-3 and N-1, matching the result.

Question 5

E.O. Lawrence was awarded the 1939 Physics Nobel Prize for invention and development of

Accepted Answer

cyclotron. E.O. Lawrence is famous for inventing the cyclotron, a compact particle accelerator. This device was central to his Nobel Prize recognition in 1939 for its invention and development.

Question 6

Calculate the electrostatic potential energy at the instant when the alpha particle stops?

Accepted Answer

$ 36.3 \mathrm{MeV} $. When the alpha particle stops momentarily, its kinetic energy is zero, so the electrostatic potential energy equals the initial kinetic energy. Therefore the potential energy at that instant is 36.3 MeV.

Question 7

A radioactive material decays by simultaneous emission of two particles with half-lives 1620 yr and 810 yr respectively. The time in years after which one-fourth of material remains, is

Accepted Answer

3240 yr. For simultaneous independent decays, the total decay constant is the sum of the individual constants. Using half-life relations, this gives an effective half-life of 1080 yr, so reaching one-fourth remaining takes two half-lives, i.e. 3240 yr.

Question 8

The nuclear reaction is given as $ _{6} C^{11} \rightarrow_{5} B^{11}+\beta+X . $ Here, $ X $ is?

Accepted Answer

A neutrino. Carbon-11 to boron-11 keeps mass number the same while atomic number drops by 1, which is characteristic of beta-plus decay or electron capture; with a beta particle shown, the missing accompanying particle is a neutrino to conserve lepton number and energy-momentum. The correct choice is a neutrino.

Question 9

Consider two nuclei of the same radioactive nuclide. One of the nuclei was created in a supernova explosion 5 billion years ago. The probability of decay during the next time is.

Accepted Answer

Independent of the time of creation. For a given nuclide, each nucleus has the same decay constant, so the probability of decaying in the next interval depends only on that constant and the interval length. The age or time of creation does not change the decay probability for the next moment.

Question 10

Which of the following is a best nuclear fuel?

Accepted Answer

Plutonium 239. Plutonium-239 is a fissile isotope, meaning it readily undergoes fission with slow neutrons and releases a large amount of energy. The other options are not as suitable as nuclear fuel because they are either not commonly fissile or are less practical as fuel isotopes.

Question 11

The radioactive decay of uranium into thorium is expressed by the equation $ 92 U^{238} \rightarrow 90 T h^{234}+X $ Where $ X $ is

Accepted Answer

an alpha particle. The radioactive decay of uranium into thorium involves the emission of an alpha particle, making option D the correct answer. [AI-generated key — verify before high-stakes use]

Question 12

Health hazards related to nuclear radiations are:

Accepted Answer

All of the above.. Nuclear radiation is ionizing, so it can damage DNA and cells. That damage can lead to cancer, inherited or developmental deformities, and gene mutations, so all listed hazards are correct.

NEET Physics: Nuclear Physics questions with solutions

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