Question

An Atom X has a mass number of 12 and contains 6 electrons. State the atomic number of X and the number of neutrons it contains.
A.6, 6
B.6, 12
C.12, 6
D.12, 12

Answer 1

To answer the above question, we need to know how an atom is represented and written in symbols. We further need to know about the subatomic particles and how its count affects the mass number and the atomic number of an atom.

Complete step by step answer:
An atom consists of electrons, protons and neutrons. Electrons are negatively charged, Protons are positively charged and neutrons do not contain any kind of charge. The atomic mass of an atom is the total count of its neutrons and protons. And the atomic number of an Atom is represented by the count of its proton.
Atoms are represented by capital letters. Normally having the first letter of their name. The atomic number of the Atom is written on the right-hand side as a superscript of the symbol. And the atomic mass of the atom is written on the left-hand side as a subscript of the symbol.
Now in the above question, we are provided with the mass number of the atom and the count of its electrons.
Atomic mass $(A)$ is 12
Number of electrons is 6
We know that the count of proton and electron is equal in the atom and hence the proton count of this atom is 6.
Also, the atomic number of the Atom is equal to its proton count. Therefore,
Atomic number=6
Now we know that;
$A = {\;{ }}neutrons + protons$
$\Rightarrow$ $12 = neutrons + 6$
$\Rightarrow$ $Neutrons = 12 - 6$
\Rightarrow $$$\;Neutrons = 6$$ Hence, the atomic number is 6 and the total number of neutrons is 6 **So, the correct option isA$ .**

Note:
Several atoms are known to have the same first letters. In case of these types of atoms, the atoms are symbolized by including the second letter of the atom. Many atoms which are known, are not symbolised by their scientific name but are represented by the first letters of their Latin names.