1. Check Statement I

A primary standard in volumetric analysis should be:

• highly pure,
• stable,
• non-hygroscopic,
• have high molar mass,
• and should allow accurate weighing.

Potassium dichromate, $\mathrm{K_2Cr_2O_7}$, is commonly used as a primary standard oxidizing agent because it is:

• available in pure form,
• stable in air,
• non-hygroscopic,
• and can be weighed accurately.

Sodium dichromate, $\mathrm{Na_2Cr_2O_7}$, is more hygroscopic/deliquescent and is therefore less suitable as a primary standard.

So, Statement I is true.

2. Check Statement II

Statement II says:

$\mathrm{K_2Cr_2O_7}$ has a higher solubility in water than $\mathrm{Na_2Cr_2O_7}$.

This is incorrect. In general, sodium salts are more soluble in water than corresponding potassium salts. In particular, $\mathrm{Na_2Cr_2O_7}$ is more soluble in water than $\mathrm{K_2Cr_2O_7}$.

Hence, Statement II is false.

3. Choose the correct option

• Statement I: True
• Statement II: False

Therefore, the correct option is:

$\boxed{\text{A}}$

4. Comparison with stored correct answer

Stored correct answer = A

My derived answer = A

So, the answer agrees with the stored correct answer.