Question

Based on the reactivities of the elements involved, which reaction will form products that are more stable than the reactants?
A.
2AlBr3 + 3Zn → 3ZnBr2 + 2Al
B.
CaBr2 + 2Na → 2NaBr + Ca
C.
MgBr2 + H2 → 2HBr + Mg
D.
BaBr2 + Ca → CaBr2 + Ba
E.
2LiBr + Ba → BaBr2 + 2Li

Answer 1

Answer : The correct option is, (B)

Explanation :

According to the reactivity series of the elements, a chemical reaction occurs when the most reactive element displace the least reactive element and form more stable products as compared to the reactants.

Option A reaction : $2AlBr_3+3Zn\rightarrow \text{No reaction}$

In this, no reaction will occur because zinc is less reactive metal as compared to aluminium. So, zinc will not displace the aluminium.

Option B reaction : $CaBr_2+2Na\rightarrow 2NaBr+Ca$

In this, the reaction will occur because sodium is more reactive metal as compared to calcium. So, sodium will displace the calcium easily.

Option C reaction : $MgBr_2+H_2\rightarrow \text{No reaction}$

In this, no reaction will occur because hydrogen is less reactive metal as compared to magnesium. So, hydrogen will not displace the magnesium.

Option D reaction : $BaBr_2+Ca\rightarrow \text{No reaction}$

In this, no reaction will occur because calcium is less reactive metal as compared to barium. So, calcium will not displace the barium.

Option E reaction : $2LiBr+Ba\rightarrow \text{No reaction}$

In this, no reaction will occur because barium is less reactive metal as compared to lithium. So, barium will not displace the lithium.

Hence, the option B reaction will form products that are more stable than the reactants.

The reactivity series of the elements are shown below.