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

Options

A. Decrease twice
B. Increase two fold
C. Remain unchanged
D. Be a function of the molecular mass of the substance

Answer

To solve the question, we need to understand the relationship between the mass of a carbon atom, the relative atomic mass unit (amu), and the concept of moles in chemistry.

### Step-by-Step Solution:

1. **Understanding Atomic Mass Unit (amu)**:
- The atomic mass unit (amu) is defined based on the mass of carbon-12. Specifically, 1 amu is defined as 1/12 of the mass of a carbon-12 atom.

2. **Changing the Reference**:
- The question states that we consider 1/6 instead of 1/12. This implies that we are redefining the atomic mass unit based on a different reference point.

3. **Calculating the New amu**:
- If we take the mass of a carbon atom as 1/6 of its original mass (which is 1/12 of C-12), we can calculate the new relative atomic mass unit.
- Therefore, if the mass of carbon is now considered as 1/6 of the mass of C-12, we can express this as:
\[ 1 \text{ amu (new)} = \frac{1}{6} \text{ mass of C-12} \]

4. **Mass of One Mole of Substance**:
- The mass of one mole of a substance in grams is numerically equal to its molar mass in amu.
- Since we have redefined the amu, we need to find out how this affects the mass of one mole of a substance.
- If 1 amu (new) = 1/6 of the mass of C-12, then:
\[ \text{Mass of one mole of substance} = 6 \text{ grams} \]
- This is because 1 mole contains Avogadro's number of atoms, and if we redefine the amu, the mass of one mole will also be scaled accordingly.

5. **Conclusion**:
- Therefore, if we consider 1/6 in place of 1/12 for the mass of carbon atom, the mass of one mole of a substance will be 6 grams.

### Final Answer:
The mass of one mole of a substance will be 6 grams.