MCQ
Which atom contains exactly 15 neutrons?
- AP32 (atomic number =17)
- BS32 (atomic number =16)
- CO15 (atomic number =8)
- DN15 (atomic number =7)
Explanation:
mass number = no.of protons + no.of neutrons
Given that mass number of P = 32
Atomic number (no. of electrons = no. of protons) = 17
Number of neutrons = 32 − 17 = 15
Hence, P satisfies the requirement.
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Diamagnetic substances are
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(a) Feebly attracted by magnets |
(b) Strongly attracted by magnets |
|
(c) Feebly repelled by magnets |
(d) Strongly repelled by magnets |
The unit of focal power of a lens is
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(a) Watt |
(b) Horse power |
(c) Dioptre |
(d) Lux |
Assertion : The electrical conductivity of earth’s atmosphere decrease with altitude.
Reason : The high energy particles (i.e. g-rays and cosmic rays) coming from outer space and entering our earth’s atmosphere causes ionisation of the atoms of the gases present there and the pressure of gases decreases with increase in altitude.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If assertion is false but reason is true. |
The retarding potential for having zero photo-electron current
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(a) Is proportional to the wavelength of incident light |
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(b) Increases uniformly with the increase in the wavelength of incident light |
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(c) Is proportional to the frequency of incident light |
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(d) Increases uniformly with the increase in the frequency of incident light wave |