Physics
A nucleus of an atom consists of 146 neutrons and 95 protons. It decays after emitting an alpha particle. How many protons and neutrons are left in the nucleus after an alpha emission?
- protons = 93, neutrons = 144
- protons = 95, neutrons = 142
- protons = 89, neutrons = 144
- protons = 89, neutrons = 142
Answer
protons = 93, neutrons = 144
Reason — An alpha particle consists of two protons and two neutrons. Emission of alpha particle reduces the number of protons by 2 and also the number of neutrons by 2. Hence, number of protons = 95 - 2 = 93 and number of neutrons = 146 - 2 = 144.
Related Questions
For a convex lens, the minimum distance between an object and its real image in terms of focal length (f) of a given lens must be:
- 1.5 f
- 2.5 f
- 2 f
- 4 f
For burning of coal in a thermoelectric station, the energy conversion taking place is:
- chemical to heat to mechanical
- chemical to heat to mechanical to electrical
- chemical to heat to light
- heat to chemical to mechanical
Assertion: Infrared radiations travel long distances through dense fog and mist.
Reason: Infrared radiations undergoes minimal scattering in earth's atmosphere
- both assertion and reason are true.
- both assertion and reason are false.
- assertion is false but reason is true.
- assertion is true reason is false.
The kinetic energy of a given body depends on the:
- position
- centre of gravity of body
- momentum
- displacement