Question

There are 42 protons and 53 neutrons in the atom of an element. This element is represented as:
(A) $ _{42}{{X}^{95}} $
(B) $ _{42}{{X}^{53}} $
(C) $ _{53}{{X}^{42}} $
(D) $ _{95}{{X}^{42}} $

Answer 1

Hint
We know that the atomic number or we can also say that the proton number of a chemical element is the number of protons found in the nucleus of every atom of that element. The atomic number uniquely identifies a chemical element. It is identical to the charge number of the nucleus. On the other hand, the atomic mass number also known as nucleon number is defined as the total number of protons and neutrons in an atomic nucleus taken together. Based on this concept we have to solve this question.

Complete step by step answer
In general, an element is always represented in the form of $ _{\text{Z}}{{\text{X}}^{\text{A}}} $ where,
 $ \mathrm{A}= $ mass number and $ \mathrm{Z}= $ proton number
Given that,
 $ \mathrm{Z}=42 $ and the number of neutrons is $ \text{N}=53 $
Thus, we get the mass number as
Total number of protons + Total number of neutrons
Hence, we get,
 $ A=Z+N=42+53=95 $
Therefore, with the mass number being 95 and the number of protons being 42, the element can be represented as $ { }_{42} \mathrm{X}^{95} $ .
Thus, the element will be $ { }_{42} \mathrm{X}^{95} $ .
Therefore, the correct answer is Option (A).

Note
It should be known to us that the electrons are fundamental particles so they cannot be decomposed into the constituents. They are therefore not made or composed. An electron acts as a point charge and a point mass. We can never see the subatomic particles directly, but can only infer from observation of such indirect effects like tracks. If there are many of them and they are emitting some radiation, and also if we shine some radiation on them and receive back the response this will also constitute a kind of seeing.