Question

A certain element consists of two stable isotopes, one with mass 10.0129 with an abundance of 19.78%, and the second with mass 11.00931 and an abundance of 80.22%. What is the element

Answer 1

Boron

Step-by-step explanation:

Step 1: Given data

• Mass of the isotope 1 (m₁): 10.0129 u

• Abundance of the isotope 1 (A₁): 19.78% (0.1978)

• Mass of the isotope 2 (m₂): 11.00931 u

• Abundance of the isotope 2 (A₂): 80.22% (0.8022)

Step 2: Calculate the average atomic mass (m) of the element

We will use the following expression.

m = m₁ × A₁ + m₂ × A₂

m = 10.0129 u × 0.1978 + 11.00931 u × 0.8022

m = 10.81 u

The element with an m = 10.81 u is Boron.