Question

The correct statements among (a) to (b) are: (a) saline hydrides produce $H_2$ gas when reacted with ${H2O}$. (b) reaction of $LiAH_4$ with $BF_3$ leads to $B_2H_6$. (c) $PH_3$ and $CH_4$ are electron - rich and electronprecise hydrides, respectively. (d) HF and $CH_4$ are called as molecular hydrides.

• A. (c) and (d) only
• B. (a), (b) and (c) only
• C. (a), (b), (c) and (d)
• D. (a), (c) and (d) only

Answer 1

The Correct Option is C

 To determine which statements among (a) to (d) are correct, we need to analyze each one based on chemical reactions and properties:

1. Statement (a): "Saline hydrides produce \(H_2\) gas when reacted with \(H_2O\)."
   • Saline hydrides, such as sodium hydride (NaH), react with water to produce hydrogen gas. The general reaction is: \(NaH + H_2O \rightarrow NaOH + H_2\). This statement is correct.
2. Statement (b): "Reaction of \(LiAlH_4\) with \(BF_3\) leads to \(B_2H_6\)."
   • The reaction between lithium aluminum hydride (LiAlH₄) and boron trifluoride (BF₃) indeed produces diborane (B₂H₆). The reaction occurs as: \(2LiAlH_4 + BF_3 \rightarrow B_2H_6 + 2LiF + 2AlF_3\). Hence, this statement is correct.
3. Statement (c): "\(PH_3\) and \(CH_4\) are electron-rich and electron-precise hydrides, respectively."
   • Phosphine (PH₃) is an electron-rich compound as it has a lone pair of electrons, while methane (CH₄) has exactly the number of bonds needed to fill the valence shell of carbon, making it an electron-precise compound. This statement is correct.
4. Statement (d): "HF and \(CH_4\) are called as molecular hydrides."
   • Both hydrogen fluoride (HF) and methane (CH₄) are molecular hydrides. HF is a polar covalent hydride, while CH₄ is a nonpolar covalent hydride. Thus, this statement is correct.

Based on the analysis, all given statements (a), (b), (c), and (d) are correct. Therefore, the correct option is (a), (b), (c), and (d).