Question

Which type of redox reaction leads to the following?

(a) An increase in the number of substances

(b) A decrease in the number of substances

(c) No change in the number of substances

Short answer

You need to write which type of redox reaction leads to an increase in the number of substances.

Step-by-step solution

Solution of the problem

The redox reaction which leads to an increase in the number of substances is decomposition reaction.

Explanation of the Decomposition Reaction

In decomposition reaction, one compound is decomposed and forms one or more products. In this type of reaction, one of the products is in element form.

There are two types of decomposition redox reaction: thermal decomposition and electrolyte decomposition reactions.

In thermal decomposition reaction, heat is the key factor for decomposition.

In electrolyte decomposition reaction, electrical energy is the key factor for decomposition.

A general decomposition redox reaction is

$Z\to X+Y$

Conclusion

A decomposition redox reaction leads to an increase in the number of substances. You need to write which type of redox reaction leads to a decrease in the number of substances.

Solution of the problem

The redox reaction which leads to a decrease in the number of substances is combination reaction.

Explanation of combination reaction

In combination reaction, two or more reactants combine to form a single product. In this type of reaction, one of the reactants is in element form.

There are two types of combination redox reaction:

First one, when two elements combine to form a product.

Second one, when one compound and one element combine to form a product.

A general combination redox reaction is

$X+Y\to Z$

Conclusion

A combination redox reaction leads to a decrease in the number of substances. You need to write which type of redox reaction leads to no change in the number of substances.

Solution of the Problem

The redox reaction which leads to no change in the number of substances is displacement reaction.

Explanation of displacement reaction

In displacement reaction, no of substances on the both side of the equation remains same but the atoms exchange places to form the product.

There are two types of displacement redox reaction: double displacement reaction and single displacement reaction.

In double displacement reaction, all the reactants are compounds.

In single displacement reaction, one of the reactants is in element form.

A general displacement redox reaction is

$AB+CD\to AD+CB$

$AB+CD\to AD+CB$

Conclusion

A displacement redox reaction leads to no change in the number of substances.