A chemical reaction involving substances A and B stops when B is completely used. B is thea. excess reactantb. limiting reactantc. primary reactantd. primary product

If all reactant will consumed, the reaction will stop. The reactant B is a limiting reactant in the reaction.

Limiting Reactant:

This is the reactant that limits the product formation during the reaction. If all reactant will consumed, the reaction will stop.

Excess reactant:

This is the reactant that present in the excess amount and react with whole limiting reactant. For example: Oxygen in the environment.

The reaction stop when all reactant B is used.

Therefore the reactant B is a limiting reactant in the reaction.

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B is the limiting reactant

Explanation:

Limiting Reactant is the reactant in a chemical reaction that limits the amount of product that can be formed. The reaction will stop when all of the limiting reactant is consumed.

The excess reactant is the reactant that remains even whn the reaction is complete.

As it is given that chemical reaction stops when B is completely used, hat means B is the limiting reagent.