GK
CHEMISTRY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the number of protons
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the number of protons and neutrons
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the number of neutrons
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the number of protons and electrons
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Detailed explanation-1: -The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).
Detailed explanation-2: -Together, the number of protons and the number of neutrons determine an element’s mass number: mass number = protons + neutrons. If you want to calculate how many neutrons an atom has, you can simply subtract the number of protons, or atomic number, from the mass number.
Detailed explanation-3: -The mass number tells us the nucleus contains 19 particles in total. Since 9 of these are protons, the other 10 are neutrons. We call it the mass number because virtually all the mass in an atom comes from the protons and neutrons-electrons weigh about 1/2000th of the mass of a proton or neutron.