Question

exam 1: atomic theory/structure
how many neutrons does zinc - 70 contain?
100
40
30
130

Explanation:

Step1: Recall zinc's atomic number

Zinc's atomic number is 30.

Step2: Calculate neutrons

Number of neutrons = mass - number - atomic number. For Zinc - 70, 70 - 30 = 40.

Answer:

40 (corresponds to the second option)