Question

Two isotopes of Uranium have 92 electrons each and have 144, 148 neutrons respectively.

Mass numbers of these two isotopes will be respectively

(A)237 ,236

(B) 236 ,237

(C) 236 ,238

(D)238 ,236​

Answer 1

Answer:

none of these is correct

Explanation:

as 92+144=236

and 92+148=240

Answer 2

Mass numbers of these two isotopes will be respectively 236 and 240.

• The mass number of an isotope or an atom is defined as the sum of its number of protons and the number of neutrons in the nucleus.
• Again the number of electrons is equal to the number of protons.
• So, the mass number of one isotope is 144+92=236 and the mass number of the other isotope is 148+92=240.