Respiratory Quotient (Coefficient) is the ratio of CO2 produced to O2 consumed in the body (AKA metabolism).
Specifically, for carbohydrates, their rate of metabolism is equal, meaning that their exchange of O2 for CO2 molecules is the same number. This gives carbohydrates a Respiratory quotient of 1:1 or just 1.
The equation below shows the oxidation of glucose and it demonstrates the 1:1 exchange in bold.