31.

Assertion: On going away from a point charge or a small electric dipole, electric field decreases at the same rate in both the cases. 

Reason: Electric field is inversely proportional to square of distance from the charge or on electric dipole.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• if both assertion and reason are false.

Assertion: If a conductor is given charge then no excess inner charge appears. 

Reason: Electric field inside conductor is zero.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  Magnetic lines forms closed loops in nature. 

Reason: Mono-magnetic pole does not exist in nature.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion: Gaussian surface is considered carefully. 

Reason:  The point where electric field to be calculated should be with in the surface

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion: Electromagnetic radiations exert pressure. 

Reason:  Electromagnetic-waves carry both momentum and energy.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  Total current entering a circuit is equal to leaving the circuit by Kirchhoff's law. 

Reason:  It is based on conservation of energy.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  Magnetic field is useful in producing parallel beam of charged particle. 

Reason:  Magnetic field inhibits the motion of charged particle moving across it.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

For satellite communication which wave is used

• Space wave

• Sky wave

• Ground wave

• Microwave

In nuclear fission, which of the following quantity is conserved?

• Energy

• Mass

• Momentum

• Both energy and mass

When a slow neutron is captured by a ${}_{92}{}^{235}\mathrm{U}$ nucleus, a fission energy releasing 200 MeV. If power of nuclear reactor is 100 W then rate of nuclear fission is

• 3.6 × 10⁶ s^-1

• 3.1 × 10¹² s^-1

• 1.8 × 10⁴ s^-1

• 4.1 × 10⁶ s^-1