Answer:
P and Q
Q and R
Explanation:
To begin, we must bear in mind the meaning of isotope.
Isotopes are atoms having the same atomic number (i.e proton) but different mass number due to the difference in the neutron number present in the atoms involved.
Thus, we shall write out the number of protons, neutrons and electrons present in the model given above. This is given:
Model P:
Proton = 12
Neutron = 13
Electron = 13
Model Q:
Proton = 12
Neutron = 12
Electron = 13
Model R:
Proton = 12
Neutron = 13
Electron = 12
From the above data, we can say that:
1. P and Q are isotope since they have different Neutron number.
2. P and R are not isotope since they have the same Neutron number.
3. Q and R are isotope since they have different Neutron number.
