Question

chlorine has an atomic number of 17. how many neutrons are present in an isotope of chlorine with a mass of 35?
17
53
35
18

Explanation:

Step1: Recall atomic number and mass number relationship

The mass number ($A$) is the sum of protons ($p$) and neutrons ($n$), and the atomic number ($Z$) is equal to the number of protons. So $A=p + n$ and $Z = p$.

Step2: Identify given values

The atomic number of chlorine $Z=17$, so the number of protons $p = 17$. The mass number of the chlorine - isotope $A = 35$.

Step3: Calculate number of neutrons

We know that $n=A - p$. Substitute $A = 35$ and $p = 17$ into the formula: $n=35 - 17=18$.

Answer:

18 (corresponding to the fourth option)