Question

what particle has 10 protons and 11 neutrons?
5
b
10.81
20
ca
40.08
10
ne
20.18
b - 11
ca - 21
ne - 21

Explanation:

Step1: Recall atomic number concept

The atomic number ($Z$) is equal to the number of protons. Given 10 protons, the atomic number is 10.

Step2: Recall mass number formula

The mass number ($A$) is the sum of protons ($p$) and neutrons ($n$). So $A=p + n$. Here $p = 10$ and $n=11$, then $A=10 + 11=21$.

Step3: Identify the element

From the periodic - table information, the element with atomic number 10 is Ne (Neon).

Answer:

Ne - 21