Question Discussion & Solution

CONCEPT:

Nuclear reactor:

• In a nuclear reactor, the energy is generated by a nuclear fission reaction.
• In a nuclear reactor, there is a concrete chamber and in this concrete chamber, there is a steel vessel. In this steel vessel, the nuclear fission reaction takes place.
• Fuel rods: Fuel rods are placed inside the steel chamber.
  • These rods are made of fissionable material. Generally, fuel rods are made of uranium-235, thorium, etc.
• Moderator: It is used to decrease the speed of fast-moving neutrons.
• Control rods: These rods are placed between the fuel rods. It is used to control the chain reaction. Control rods are generally made of cadmium.
  • The nuclear reactors are controlled by means of control rods which are made of a strongly neutron-absorbent material such as boron or cadmium (Cd).
• Coolant: It is used to absorb heat produced during the reaction.

EXPLANATION:

• Moderators are used to slow down the neutrons in order to carry out effective nuclear fission and also absorb neutrons. 
• The main reason why heavy water is used as the moderator is that it captures less number of neutrons compared to normal water Hence, option 2 is the answer. 

Logic: second Number = First Number × 2 + 1

Third Number = First Number ÷ 2 + 1

(56, 113, 29) → 56 × 2 + 1 = 113, 56 ÷ 2 + 1 → 29

(68, 137, 33) → 68 × 2 + 1 = 137, 68 ÷ 2 + 1 → 35 ≠ 33

( 72, 145, 37) → 72 × 2 + 1 = 145, 72 ÷ 2 + 1 → 37

(84, 169, 43) → 84 × 2 + 1 = 169, 84 ÷ 2 + 1 → 43

The pattern followed here is:

Hence, ‘DW’ complete the series.

When the question figure is merged with the figure in option 3, the complete pattern can be seen as:

Hence, the figure in option (3) is the correct answer.

final is used to apply restrictions on class, method, and variable. final is a keyword.

finally is used to place important code, it will be executed whether an exception is handled or not.

System is a class. finalize and main are methods.