When an enzyme doesn't work properly it is said to be . Three things that can cause this are , and

Explanation:

When enzyme does not work properly it is said to be inactive and this affect its efficiency.

Substrate concentration - Enzyme requires adequate substrate concentration to be effective, when the concentration is high the enzyme activity increases and when it is low it decreases.

Temperature - Enzymes are more active at specific temperature at very high temperature enzyme can be denatured leading to a loss of its activity. Hence, enzyme should be made to work at its optimum.

pH- Enzymes are active at specific pH, when the pH is altered enzymatic activity may be reduced or enzyme become inactive. Hence, pH of enzymes should be maitained.

a . into the substance, and the substance changed into a gas.

Explanation:

The correct answer would be that the scientists transferred energy into the substance, and the substance changed into gas.

Since the molecules of the substance are already in motion before the addition of energy, it means the substance is in liquid form as opposed to solid. Further addition of energy will result in the molecules of liquid moving faster and change phase into a gas.

The molecules of solids are stationary initially, addition of energy will result into liquid and not directly into gas, unless the substance has the capacity to sublime.

Hence, the correct option is a.