Question

Which of the following reactions give phosphine? 
i. Reaction of calcium phosphide with water
ii. Heating white phosphorus with concentrated NaOH solution in an inert atmosphere
iii. Heating red phosphorus with alkali

• A. \( i, ii \text{ only} \)
• B. \( i, ii, iii \)
• C. \( ii, iii \text{ only} \)
• D. \( i, iii \text{ only} \)

Hint:

Phosphine is typically produced by hydrolysis of metal phosphides or by reduction of phosphorus compounds in basic conditions. However, red phosphorus does not react with alkali to give phosphine.

Answer 1

The Correct Option is A

Step 1: Understanding the Formation of Phosphine 
Phosphine (\(PH_3\)) is a gaseous compound that can be produced by the hydrolysis of phosphides and by heating phosphorus with a strong base. Step 2: Checking the Given Reactions 
1. Reaction of calcium phosphide (\(Ca_3P_2\)) with water: \[ Ca_3P_2 + 6H_2O \rightarrow 2PH_3 + 3Ca(OH)_2 \] This reaction produces phosphine. 2. Heating white phosphorus with concentrated NaOH in an inert atmosphere: \[ P_4 + 4NaOH + 2H_2O \rightarrow 2PH_3 + 4NaH_2PO_2 \] This reaction also forms phosphine. 3. Heating red phosphorus with alkali does not produce phosphine directly.  This reaction does not yield phosphine. 
Step 3: Conclusion 
Since reactions (i) and (ii) lead to the formation of phosphine, the correct answer is: \[ \boxed{i, ii \text{ only}} \]