An isotope has 21 neutrons and a mass number of 40, it has 19 electrons and protons and 21 neutrons. true or false plz explain the answer

True

Explanation:

Given parameters:

   Number of neutrons = 21

   Mass number  = 40

Unknown:

Number of electrons = 19

Number of neutrons  = 21

Solution:

To find verify whether it is true or false, we must understand the relationship between the given species.

  Protons are the positively charged particles

  Neutrons do not carry any charge

  electrons are the negatively charged particles

Mass number  = number of protons + neutrons

   Number of protons  = 40 - 21 = 19

In an atom, the number of protons and electrons are the same for charge stability.

 Number of electrons  = 19

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