Answer:
a.
P = 3 , N = 4
b.
P = 8 , N = 8
c.
P = 90 , N = 142
d.
P = 94 , N = 145
Explanation:
Mass number = Number of protons + Number of neutrons
Also,
Atomic number = Number of protons
Li - 7
Given, Mass number of Lithium = 7
For lithium, atomic number = 3
So,
Number of protons = 3
Number of neutrons = Mass number - Number of protons = 7 - 3 = 4
O - 16
Given, Mass number of oxygen = 16
For oxygen, atomic number = 8
So,
Number of protons = 8
Number of neutrons = Mass number - Number of protons = 16 - 8 = 8
Th - 232
Given, Mass number of Thorium = 232
For Thorium, atomic number = 90
So,
Number of protons = 90
Number of neutrons = Mass number - Number of protons = 232 - 90 = 142
Pu - 239
Given, Mass number of Plutonium = 239
For Plutonium, atomic number = 94
So,
Number of protons = 94
Number of neutrons = Mass number - Number of protons = 239 - 94 = 145
