Question

Identify atoms that are isotopes in each of the following sets of four atoms.

Answer 1

Answer: The correct answer is Option c.

Explanation:

Isotopes are defined as the chemical species which have same number of protons but differ in the number of neutrons.

The general isotopic representation is $_{Z}^A\textrm{X}$

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

The isotopes having same atomic number are the isotopes of same element.

So, the isotopes are $_{11}^{23}\textrm{X},_{11}^{24}\textrm{X}\text{ and }_{11}^{25}\textrm{X}$

Hence, the correct answer is Option c.

Answer 2

Isotopes are elements with similar chemical properties meaning same atomic number, but varying atomic masses, meaning different number of neutrons in the element.  It can be easily determined knowing this and viewing the subscripts of the element symbol.  The lower subscript is the atomic number and the higher subscript is the atomic mass.  Simply look for similar atomic numbers and differing atomic masses in the sets.

a) 1, 2 are isotopes

b) 1, 3 are isotopes

c) 1, 2, 3 are isotopes

d) none are isotopes