List down four (4) possible reasons why percent yield is usually less than 100%?

Percent yield is the percent ratio of actual yield to the theoretical yield. It is calculated to be the experimental yield divided by theoretical yield multiplied by 100%. If the actual and theoretical yield ​are the same, the percent yield is 100%.

Usually, percent yield is lower than 100% because :

1. The actual yield is often less than the theoretical value.

2. Incomplete reactions, in which some of the reactants do not react to form the product.

3. Practical losses during the experiment, such as during pouring or filtering.

4. Side reactions (unwanted reactions that compete with the desired reaction).