What is the energy of photon whose wavelength is 6840 $\stackrel{\circ }{\mathrm{A}}$ ?

• 1.81 eV

• 3.6 eV

• $-$ 13.6 eV

• 12.1 eV

Calculate power output of  ${}_{92}{}^{235}\mathrm{U}$ reactor, if it is takes 30 days to use up 2 kg of fuel, and if each fission gives  185 MeV of useable energy. Avogadro's number = 6 × 10²³ / mol?

• 56.3 MW

• 60.3 MW

• 58.3 MW

• 54.3 MW

A transistor is a/an

• chip

• insulator

• semiconductor

• metal

The number 0 (zero) is required for

• transistor

• abacus

• computer

• calculator

Assertion:  Goggles have zero power.

Reason: Radius of curvature of both sides of lens is same.

• 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: A white source of light during interference forms only white and black fringes.

Reason: Width of fringe is inversely proportional to the wavelength of the light used.

• 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: Heavy water is a better moderator than normal water.

Reason: Heavy water absorbs neutrons more efficiently than normal water.

• 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

58.

Assertion: In a metal all the free electrons have same energy.

Reason: : Electrons do not obey Pauli's Exclusion principle

• 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 and reason is false

• If both assertion and reason are false

Assertion:  Optical fibres are used for telecommunication.

Reason: Optical fibres are based on the phenomenon of total internal reflection.

• 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:  ⁹⁴Sr from the radioactive fall out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells. 

Reason: The energetics  β-particles emitted in the decay of  ⁹⁴Sr damage the bone marrow.

• 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