Which one of the following is not the standard for atomic mass?

Options

A. `""_(1)^(1)H`
B. `""_(6)^(12)C`
C. `""_(6)^(14)C`
D. `""_(8)^(16)O`

Answer

To determine which option is not a standard for atomic mass, we need to understand what the standard atomic masses are and how they are defined. Here’s a step-by-step solution:

### Step 1: Understand Atomic Mass
Atomic mass is defined as the mass of an atom, typically measured in atomic mass units (amu). The standard atomic mass of an element is usually based on a specific isotope of that element.

### Step 2: Identify Common Standards
The most commonly used standard for atomic mass is the isotope Carbon-12 (C-12), which is assigned an atomic mass of exactly 12 amu. Other isotopes, such as Hydrogen-1 (H-1) with an atomic mass of approximately 1 amu, are also used as standards.

### Step 3: Evaluate the Options
To answer the question, we need to evaluate the provided options (not listed in the question but assumed to be given in the context) and identify which one does not represent a standard atomic mass.

### Step 4: Determine the Correct Answer
If one of the options is an isotope that is not commonly used as a standard (for example, an isotope of an element that is not stable or not used in defining atomic mass), that would be the correct answer. Based on the context provided in the video transcript, it suggests that option 3 is the correct answer because it does not represent a standard atomic mass.

### Final Answer
The option that is not a standard for atomic mass is **option 3**.

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