Consider the following statement
I 12 molecules of HCl is a dozen.
II 144 molecules of HCl is a gross.
`6.022xx10^(23)` molecules of HCl is a mole.
select the correct statement

Options

A. I and III
B. II and III
C. I and III
D. all of these

Answer

To determine the correctness of the statements regarding molecules of HCl, we will analyze each statement step by step.

### Step 1: Analyze Statement I
**Statement I:** 12 molecules of HCl is a dozen.

- A dozen is defined as 12 units of any item. Therefore, if we have 12 molecules of HCl, we can indeed say that we have a dozen of HCl molecules.
- **Conclusion:** This statement is **true**.

### Step 2: Analyze Statement II
**Statement II:** 144 molecules of HCl is a gross.

- A gross is defined as 12 dozen, which is equivalent to 12 x 12 = 144 units. Therefore, if we have 144 molecules of HCl, we can correctly say that we have a gross of HCl molecules.
- **Conclusion:** This statement is **true**.

### Step 3: Analyze Statement III
**Statement III:** `6.022 x 10^23` molecules of HCl is a mole.

- The number `6.022 x 10^23` is known as Avogadro's number, which defines the number of particles (atoms, molecules, etc.) in one mole of a substance. Hence, if we have `6.022 x 10^23` molecules of HCl, we can say that we have one mole of HCl.
- **Conclusion:** This statement is **true**.

### Final Conclusion
Since all three statements are true, the correct answer is that all statements are correct.