Tag: isotopes and nuclear chemistry

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Questions Related to isotopes and nuclear chemistry

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

In a nuclear reactor the excess reactivity can be controlled by using _____________ rods.

  1. Lead rods

  2. Iron rods

  3. Uranium rods

  4. Cadmium rods
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lead rods 

In nuclear reactor the lead rods have the ability to control the excess reactivity by suitably absorbing the neutrons and thus making the reaction controllable. 

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Cadmium rods are used in a nuclear reactor

  1. To produce neutrons

  2. To speed up neutrons

  3. To absorb neutrons

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To absorb neutrons 

Cadmium rods are inserted in nuclear reacter to absorb the extra nucleons any keep the nuclear reaction ratio of  1:1 , also keep the reaction stable. Cadmium has a high thermal neutron absorption cross section. Therefore cadmium rods will absorb neutrons, making them unavailable to cause fission.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

In a nuclear reactor heavy water is used as a.

  1. Moderate

  2. Fuel

  3. Shield

  4. Controlling element
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Moderator 

A neutron moderator is a modium that reduces the spread of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving U-235. Heavy water is used as a moderator in nuclear reactor.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Which one moves with greatest speed :

  1. $\alpha$-rays
  2. $\beta$-rays
  3. $\gamma$-rays

  4. cathode rays
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A

Alpha particles are released by high mass, proton rich unstable nuclei. The alpha particles is a helium nucleus, it consists of two protons and two neutrons. It contains no electron to balance the two positively charged protons. Alpha particles are therefore positively charged particles moving at high speed. 

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Moderator is a substance that ..................... the neutrons in a nuclear reactor.

  1. Slow down

  2. Activates

  3. Both (a) and (b) above

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A moderator is a material used in nuclear reactors to reduce the speed of fast neutrons, thereby increasing the probability of them causing further fission in U-235 nuclei.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The amount of $U^{235}$ to be fissioned, to operate a $10\ kW$ nuclear reactor is (Approximately)

  1. $1.2 \times 10 ^ { - 5 }\ \mathrm { gm } / \mathrm { s }$
  2. $1.2 \times 10 ^ { - 7 }\ \mathrm { gm } / \mathrm { s }$
  3. $1.2 \times 10 ^ { - 9 }\ \mathrm { gm } / \mathrm { s }$
  4. $1.2 \times 10 ^ { - 11 }\ \mathrm { gm } / \mathrm { s }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using the relation P = (n * E) / t, where P is power, n is number of fissions, and E is energy per fission. 10 kW = 10,000 J/s. E = 200 MeV = 200 * 1.6 * 10^-13 J. Calculating the mass of U-235 required leads to approximately 1.2 * 10^-11 g/s.