Question

1. which of the following is the correct representation of the electron configuration of oxygen in its ground state?
2. a 100.00 - gram sample of naturally occurring boron contains 19.78 grams of boron - 10 (atomic mass = 10.01 atomic mass units) and 80.22 grams of boron - 11 (atomic mass = 11.01 atomic mass units). which numerical setup can be used to determine the atomic mass of naturally occurring boron?

(a) (0.1978)(10.01) + (0.8022)(11.01)
(b) (0.1978) (11.01) + (0.8822)(10.01)
(c) (0.1978)(10.01) x (0.8022)(11.01)
(d) (19.78)(0.1001) x (80.22)(0.1101)

Explanation:

Step1: Calculate the abundance of each isotope

The abundance of boron - 10 is \(\frac{19.78}{100}=0.1978\), and the abundance of boron - 11 is \(\frac{80.22}{100}=0.8022\).

Step2: Use the formula for atomic mass

The formula for the atomic mass of an element with two isotopes is \(M = a_1M_1 + a_2M_2\), where \(a_1\) and \(a_2\) are the abundances of the isotopes, and \(M_1\) and \(M_2\) are their atomic masses.
Substituting the values, we get \(M=(0.1978)(10.01)+(0.8022)(11.01)\)

Answer:

A. \((0.1978)(10.01)+(0.8022)(11.01)\)