Which of the following statements is false ?

Options

A. `Na_(2)Cr_(2)O_(7)` is less soluble than `K_(2)Cr_(2)O_(7)`
B. `K_(2)Cr_(2)O_(7)` is primary standard in volumetry
C. `CrO_(4)^(2-)` is tetrahedral in shape
D. `Cr_(2)O_(7)^(2-)` has a Cr-O-Cr bond

Explanation

To determine which of the statements is false, we will analyze the given statements regarding the solubility of sodium dichromate (Na2Cr2O7) and potassium dichromate (K2Cr2O7).

### Step-by-Step Solution:

1. **Understanding the Compounds**:
- Sodium dichromate (Na2Cr2O7) and potassium dichromate (K2Cr2O7) are both salts of dichromate ions (Cr2O7^2-).
- The solubility of these compounds in water can be influenced by the cation (Na+ vs. K+).

2. **Comparing Solubility**:
- Generally, potassium salts tend to be more soluble than sodium salts due to the larger size of the potassium ion (K+) compared to the sodium ion (Na+). This is because larger ions can stabilize the lattice energy better when they are solvated in water.

3. **Analyzing the Statement**:
- The statement in question is: "Na2Cr2O7 is less soluble than K2Cr2O7."
- Based on the general trend of solubility for alkali metal salts, this statement is **true**.

4. **Identifying Other Statements**:
- Without the other statements provided, we cannot directly analyze them. However, if we assume that the other statements are true, we can conclude that the only false statement must be one that contradicts the established solubility trend.

5. **Conclusion**:
- Since the statement "Na2Cr2O7 is less soluble than K2Cr2O7" is true, we need to identify any other statements that could be false. If we assume that the other statements are indeed correct, we conclude that the false statement is likely one that contradicts the solubility trend.

### Final Answer:
The false statement is likely one that contradicts the established solubility trend of dichromates, but based on the provided information, we conclude that the statement "Na2Cr2O7 is less soluble than K2Cr2O7" is **true**.