Question

Atom A has a mass number 209 and atomic number 82.
Atom B has a mass number 209 and atomic number 83.
(i) How many protons atom A has ?
(ii) How many protons atom B has ?
(iii) Are atoms A and B isotopes of the same element ?

Answer 1

Answer:

1) 82 protons are present in atom A

2) 83 protons are present in atom B

3) yes

Answer 2

Answer:

Number of protons in atom A =82

Number of protons in atom B =83

Atom A and atom B are not isotopes of same element.

Explanation:

For atom A : Mass number $=209$

                    Atomic number $=82$

We know Atomic number = Number of protons

Therefore number of protons in atom A $=82$

For atom B: Mass number $=209$

                   and,  Atomic number $=83$

Here, number of protons $=83$

Atom A and atom B has different atomic number. Therefore they are not the isotopes of the same elements. Instead of that, they have same mass number. Therefore they are isobars.