Which of the following statement(s) is/are incorrect regarding property of alkali metals ?
I. Alkali metal on reaction with water produces a gas as a by product which burns with popping sound.
II.All alkali metal hydrides are ionic in nature.

Options

A. Only I
B. Only II
C. I and II
D. None of these

Answer

To determine which statements regarding the properties of alkali metals are incorrect, let's analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement I:** "Alkali metal on reaction with water produces a gas as a by-product which burns with popping sound."

- When alkali metals react with water, they produce hydrogen gas (H₂) and a corresponding hydroxide (e.g., NaOH for sodium).
- The balanced chemical reaction can be represented as:
\[ 2M + 2H_2O \rightarrow 2MOH + H_2 \]
where M is the alkali metal.
- Hydrogen gas is indeed produced, and it burns with a characteristic popping sound when ignited.

**Conclusion for Statement I:** This statement is **correct**.

### Step 2: Analyze the Second Statement
**Statement II:** "All alkali metal hydrides are ionic in nature."

- Alkali metal hydrides (e.g., NaH, KH) are formed when alkali metals react with hydrogen.
- These hydrides are indeed ionic compounds, characterized by the presence of alkali metal cations (M⁺) and hydride anions (H⁻).
- They typically exhibit high melting points and are solid at room temperature, which is characteristic of ionic compounds.

**Conclusion for Statement II:** This statement is also **correct**.

### Step 3: Determine the Incorrect Statements
- Both statements I and II are correct. Therefore, there are no incorrect statements regarding the properties of alkali metals.

### Final Conclusion
The answer to the question is that **none of the statements are incorrect**.

### Answer: Option D (None of these)

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