What type of variable is held constant in an experiment?

A variable in an experiment which is held constant in order to assess the relationship between multiple variables, is a control variable.

Explanation:

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.