Which of the following is an example of a double-displacement reaction?

AlCl3 + 3 NaOH → Al(OH)3 + 3 NaCl

Na2O + H2O → 2 NaOH

CuCO3 → CuO + CO2

None of the above are examples of double-displacement.

A

Which of the following is a double-displacement reaction?

2 KClO3 → 2 KCl + 3 O2

Zn + 2 HCl → ZnCl2 + H2

Fe + S → FeS

None of the above are examples of double-displacement.

D

Which of the following is a double-displacement reaction?

4P + 5O2 2P2O5

6NaNO3 6NaNO2 + 3O2

2C8H18 + 25O2 16CO2 + 18H2O

H2SO4 + 2NaOH Na2SO4 + 2H2O

C

What would most likely be the products of the double-displacement reaction between AgNO3 and NaCl ?

Ag + NaNO3

AgCl + Na

AgCl + NaNO3

The reaction would not occur because Al is lower on the activity series than Na.

C

I believe #3 is wrong. The others are ok.

C is a combustion reaction. D is the double displacement.

To determine which of the given reactions are examples of double-displacement reactions, we need to understand what a double-displacement reaction is.

In a double-displacement reaction, the cations and anions from two different compounds swap places, resulting in the formation of two new compounds. This type of reaction is also known as a metathesis reaction.

Let's analyze each option:

Option A: AlCl3 + 3 NaOH → Al(OH)3 + 3 NaCl
In this reaction, the chloride ions (Cl-) from AlCl3 swap places with the hydroxide ions (OH-) from NaOH, resulting in the formation of Al(OH)3 and NaCl. This is an example of a double-displacement reaction.

Option B: Na2O + H2O → 2 NaOH
In this reaction, sodium oxide (Na2O) reacts with water (H2O) to produce sodium hydroxide (NaOH). While a chemical reaction does occur, it is not a double-displacement reaction because there is no swapping of anions between compounds.

Option C: CuCO3 → CuO + CO2
In this reaction, copper(II) carbonate (CuCO3) decomposes to form copper(II) oxide (CuO) and carbon dioxide (CO2). This is a decomposition reaction, not a double-displacement reaction.

Option D: None of the above are examples of double-displacement.
Since options A and B are examples of double-displacement reactions, this option is incorrect.

Therefore, the correct answer is option A: AlCl3 + 3 NaOH → Al(OH)3 + 3 NaCl.