Answer:
The correct answer is 265.
Step-by-step explanation:
Hello!
Let's solve this!
In the nucleus there will be 158 neutrons and as we know that in the atom there is the same amount of protons as there are electrons, there would be 106. But it says that it has a +1 charge with which we have 107 protons.
The mass of the atom will be 107 + 158 = 265.
We conclude that the correct answer is 265.