If `1//6`, in place of `1//12`, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one one of a substance will:

Options

A. be a function of the molecular mass of thesubstance
B. remain unchanged
C. increase two fold
D. decrease twice

Answer

To solve the problem, we need to analyze the implications of changing the relative atomic mass unit from 1/12 of a carbon atom to 1/6 of a carbon atom. Here’s a step-by-step breakdown:

### Step 1: Understanding the Relative Atomic Mass
The relative atomic mass of an element is typically based on the mass of a carbon atom, where 1/12 of the mass of a carbon-12 atom is defined as 1 atomic mass unit (AMU).

### Step 2: New Definition of AMU
If we take 1/6 of the mass of a carbon atom as the new relative atomic mass unit, we need to determine what this means for the value of AMU.

- The mass of a carbon atom (C) is approximately 12 AMU.
- Therefore, 1/6 of the mass of carbon would be:
\[ \text{New AMU} = \frac{1}{6} \times 12 \text{ AMU} = 2 \text{ AMU} \]

### Step 3: Avogadro's Number
Avogadro's number (N_A) is the number of particles (atoms, molecules, etc.) in one mole of a substance. Since the new AMU is now 2 AMU, we need to see how this affects the mass of one mole of a substance.

### Step 4: Mass of One Mole of Substance
The mass of one mole of a substance is given by:
\[ \text{Mass of one mole} = N_A \times \text{AMU} \]
Using the new AMU:
\[ \text{Mass of one mole} = N_A \times 2 \text{ AMU} \]

### Step 5: Comparison with Original Mass
Originally, with the old AMU (1 AMU), the mass of one mole would have been:
\[ \text{Mass of one mole} = N_A \times 1 \text{ AMU} \]
Now, since the new AMU is 2 AMU, we can see that the mass of one mole of a substance will effectively remain unchanged in terms of the numerical value of the mass in grams.

### Conclusion
Thus, even though we have changed the definition of the atomic mass unit, the mass of one mole of a substance remains unchanged because the increase in the AMU is offset by the decrease in the number of moles represented by Avogadro's number.

### Final Answer
The mass of one mole of a substance will remain unchanged.

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