Which of the following statement is true

Options

A. Acetaldehyde gives positive test with Fehling solution and Schiffs reagent
B. Tertiary alcohols gives blood red colour with victor mayer test
C. Phenol gives positive test with `NaHCO_3`
D. Only Primary amines can Give isocyanide test . ( carbylamine )

Explanation

To determine which of the statements is true, we will analyze each statement one by one based on our knowledge of organic chemistry.

### Step 1: Analyze the first statement
**Statement 1:** Acetaldehyde gives a positive test with Fehling's solution and Schiff's reagent.

- Acetaldehyde (CH₃CHO) is an aldehyde.
- Aldehydes react with Fehling's solution to produce a red precipitate of Cu₂O, indicating a positive test.
- Aldehydes also give a pink color with Schiff's reagent.

**Conclusion:** This statement is true.

### Step 2: Analyze the second statement
**Statement 2:** Tertiary alcohols give a blue color with the Victor Meyer test.

- The Victor Meyer test is used to differentiate between primary, secondary, and tertiary alcohols.
- Tertiary alcohols do not react in the Victor Meyer test because they lack a hydrogen atom on the carbon bearing the hydroxyl group (OH).
- Therefore, they do not produce a color change or any reaction.

**Conclusion:** This statement is false.

### Step 3: Analyze the third statement
**Statement 3:** Phenol gives a positive test with NaHCO₃.

- Phenol is a weak acid and does not react with sodium bicarbonate (NaHCO₃) to release carbon dioxide (CO₂).
- Since it does not liberate CO₂, it does not give a positive test with NaHCO₃.

**Conclusion:** This statement is false.

### Step 4: Analyze the fourth statement
**Statement 4:** Only primary amines can give the isocyanide test.

- The isocyanide test (or carbylamine reaction) is specific for primary amines.
- When a primary amine reacts with chloroform (CHCl₃) in the presence of a strong base (like KOH), it produces isocyanides (RNC), which have a characteristic smell.
- Secondary and tertiary amines do not undergo this reaction.

**Conclusion:** This statement is true.

### Final Conclusion
Based on the analysis:
- **True Statements:** Statement 1 and Statement 4.
- **False Statements:** Statement 2 and Statement 3.

Thus, the true statements are the first and the last statements.