Download App

Nuclei — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsNuclei1 Mark
Question
For question, statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a) (b) (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is NOT the correct explanation of A.
  3. A is true, but R is false.
  4. A is false and R is also false.
Assertion (A): For the fission of heavy nuclei, neutrons are more effective than protons.
Reason (R): Neutrons are heavier than protons.
✓

Answer

  1. Both A and R are true, but R is NOT the correct explanation of A.
Explanation:
A neutron is slightly heavier than a proton. As neutrons are charge less particles, they penetrate matter more than protons. Therefore, they are more effective than protons in fission reactions.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Assertion (A) & Reason (B) MCQ" from Nuclei→Nuclei — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

Assertion (A): When ultraviolet light is incident on a photocell, its stopping potential is $V _0$ and the maximum kinetic energy of the photoelectrons is $K _{\max }$. When the ultraviolet light is replaced by X-rays, both $V _0$ and $K _{\max }$. increase.
Reason (R): Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light.
→
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, and R is also false.
Assertion: If the length of the conductor is doubled, the drift velocity will become half of the original value (keeping potential difference unchanged).
Reason: At constant potential difference, drift velocity is inversely proportional to the length of the conductor.
→
Assertion (A) : The quantity L/R possesses the dimension of time.
Reason (R): In order to reduce the rate of increase of current through a solenoid, we should increase the time constant.
→
Assertion (A): In photoemissive cell inert gas is used.
Reason (R): inert gas in the photoemissive cell gives greater current.
→
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is NOT the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion (A): In electric circuits, wires carrying currents in opposite directions are often twisted together.
Reason (R): If the wire are not twisted together, the combination of the wires forms a current loop. 'Tile magnetic field generated by the loop might affect adjacent circuits or components.
→
For question, statements are given-one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $(a) (b) (c)$ and $(d)$ as given below. Assertion $(A$): The ratio for time taken for light emission from an atom to that for release of nuclear energy in fission is $1 : 100$.
Reason $(R)$: Time taken for the light emission from an atom is of the order of $10^{-8}s$.
→
For two statements are given-one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: $A$ bulb connected in series with a solenoid is connected to $A.C.$ source.
If a soft iron core is introduced in the solenoid, the bulb will glow brighter.
Reason: On introducing soft iron core in the solenoid, the inductance decreases.
→
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is NOT the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion (A): Light added to light can produce darkness.
Reason (R): The destructive interference of two coherent light sources may give dark fringe.
→
Assertion (A): Nuclei having mass number about 60 are least stable.
Reason(R): When two or more light nuclei are combined into a heavier nucleus then the binding energy per nucleon will decrease.
→
For question, statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a) (b) (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is NOT the correct explanation of A.
  3. A is true, but R is false.
  4. A is false and R is also false.
Assertion (A): The nuclear force becomes weak if the nucleus contains too many protons compared to neutrons.
Reason (R): The electrostatic forces weaken the nuclear force.
→