Zinc Has Five Naturally Occurring Isotopes, Zn-64, Zn-66, Zn-67, Zn-68

question 159

Multiple Choice

Zinc has five naturally occurring isotopes, Zn-64, Zn-66, Zn-67, Zn-68 and Zn-70. Calculate the atomic mass of zinc given the following abundances and atomic masses for the isotopes:
Zn-64 63.9291 u 48.61%
Zn-66 65.9260 u 27.9%
Zn-67 66.9271 u 4.1%
Zn-68 67.9248 u 18.75%
Zn-70 69.9253 u 0.62%

• A) 66.3 u
• B) 65.4 u
• C) 66.7 u
• D) 65.1 u
• E) 64.8 u

---

Definitions:

Machine Hour

A measure used to allocate costs to products or services based on the number of hours a piece of equipment is operated.

Cost-volume-profit Analysis

A managerial accounting technique used to analyze how changes in costs and volume affect a company's operating income and net income.

Break-even Analysis

A calculation and assessment method to determine the point at which revenue received equals the costs associated with producing the revenue, indicating no net loss or gain.

Estimated Fixed Costs

Predicted expenses that do not fluctuate with the level of production or sales over a certain period of time.