Question

Which of the following are not single-displacement reactions?
O A. Fe (s) + 2HCl (aq) → FeCl2(aq) + H2 (9)
B. KOH (aq) + HNO3 (aq) – H20 () + KNO3 (aq)
O C. Na2S (aq) + 2HCl (aq) + 2NaCl (aq) + H2S (g)
O D. Ca (s) + 2H20 (1) ► Ca(OH)2 (aq) + H2 (9)
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SUBMIT
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Answer 1

Answer:

$\boxed{\text{B and C }}$

Explanation:

In a single-displacement reaction, one element exchanges partners with another element in a compound.

$\textbf{A. } \rm Fe + 2HCl \longrightarrow FeCl_2 + H_2$

This is a single-displacement reaction, because the element Fe exchanges partners with H in HCl.

$\textbf{B. } \rm KOH + HNO_3 \longrightarrow H_2O + KNO_3$

This is not a single-displacement reaction, because it is a reaction between two compounds.

This is a double displacement reaction in which the K⁺ and H⁺ cations change partners with the anions.

$\textbf{C. } \rm Na_2S + 2HCl \longrightarrow 2NaCl + H_2S$

This is not a single-displacement reaction. It is another double displacement reaction, in which the Na⁺ and H⁺ cations change partners with the anions.

$\textbf{D. } \rm Ca + 2HOH \longrightarrow Ca(OH)_2 + H_2$

This is a single-displacement reaction, because the element Ca exchanges partners with H in H₂O.

$\boxed{\textbf{B and C }}$ are not single-displacement reactions.