The half-life of a chemical reaction at a particular concentration is 50 min, when the concentration of reactants is doubled, the half-life becomes 100 min. Find the order:

Zero

The correct answer is option 1. Zero.

In a zero-order reaction, the rate of the reaction is independent of the concentration of the reactants. This means that doubling the concentration of the reactants will not have any effect on the rate of the reaction. In other words, the reaction proceeds at a constant rate regardless of the concentration.

Now, let's consider the given information. Initially, the half-life of the reaction is 50 minutes at a particular concentration. This means that it takes 50 minutes for half of the reactant to be consumed.

When the concentration of the reactants is doubled, the half-life becomes 100 minutes. This means that it now takes 100 minutes for half of the reactant to be consumed.

Since doubling the concentration does not change the half-life, it indicates that the rate of the reaction remains the same. This behavior is consistent with a zero-order reaction where the rate is independent of the concentration.

If the reaction were first, second, or third order, doubling the concentration would have resulted in a different change in the half-life. For example, in a first-order reaction, doubling the concentration would halve the half-life. In a second-order reaction, doubling the concentration would double the half-life. In a third-order reaction, doubling the concentration would result in a four-fold increase in the half-life.

However, since the half-life is doubled when the concentration is doubled, it confirms that the reaction is zero order.

Therefore, the correct answer is (1) Zero order.