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CBSE

Subject

Chemistry

NEET Chemistry : Structure of Atom

Multiple Choice Questions

141.

Assertion: The absorption spectrum consists of some bright lines separated by dark spaces.
Reason: Emission spectrum consists of dark lines.

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

142.

Assertion: For Balmer series of hydrogen spectrum, the value n₁ = 2 and n₂ = 3, 4, 5.
Reason: The value of n for a Line in Balmer series of hydrogen spectrum having the highest wavelength is 4 and 6.

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

143.

During the emission of a positron from a nucleus, the mass number of the daughter element remains the same but the atomic number

is decreased by 1 unit
is decreased by 2 units·
is increased by 1 unit
remains unchanged

144.

Which of the following does not represent the mathematical expression for the Heisenberg uncertainty principle?

$∆$ x ^. $∆$ p $⩾$ h/(4 $π$ )
$∆$ x ^. $∆v$ $⩾$ h/(4 $πm$ )
$∆E$ ^. $∆t$ $⩾$ h/(4 $π$ )
$∆E$ ^. $∆x$ $⩾$ h/(4 $π$ )

145.

As per de-Broglie's formula a macroscopic particle of mass 100 g and moving at a velocity of 100 cm s^-1 will have a wavelength of

6.6 × 10^-29 cm
6.6 × 10^-30 cm
6.6 × 10^-31 cm
6.6 × 10^-32 cm

146.

Assertion : Water is used as a moderator in nuclear reactor.

Reason : Moderator is a light substance that absorb neutrons.

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 Assertion is false but Reason is true.

147.

₁₁Na²⁴ 1s radioactive and it decays to:

₉F²⁰ and $α$ -particles
₁₃Al²⁴ and positron
₁₁Na²³ and neutron
₁₂Mg²⁴ and $β$ -particles

148.

Assertion : Ionisation potential of B (atomic no.5) is less than Be (atomic no. 4).

Reason : The first electron released from Be is of p-orbital but that from B is of s-orbital.

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 Assertion is false but Reason is true.

149.

The emission spectrum of hydrogen discovered first and the region of the electromagnetic spectrum in which it belongs, respectively are

Lyman, ultraviolet
Lyman, visible
Balmer, ultraviolet
Balmer, visible

150.

Assertion: Absolute values of the internal energy of substances can not be determined.
Reason: It is impossible to determine the exact values of constituent energies of the substances.

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

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