Chapter 39, Problem 10A

To determine

Whether U-235 has more neutrons or U-238.

Explanation of Solution

Introduction:

U-235 and U-238 are the isotopes of the Uranium because the atomic numbers of the both are same but the numbers of neutrons are different.

The mass number of an atom is the sum of the number of proton and neutron. The atomic number is same as the number of proton in the nucleus of the atom.

The atomic number of U-235 and U-238 is same. So, the number of protons in the nucleus of both atoms is also same.

The mass numbers of both atoms are 238 and 235. So, U-238 has three more neutron than U-235 in the nucleus.

Conclusion:

Thus, U-238 has three more neutron than U-235 in the nucleus.