<prompt> Which of the following is the main component of soda lime used in a closed circuit?Sodium hydroxideBarium hydroxideCalcium hydroxidePotassium hydroxide  <response>: Soda lime used in a closed circuit is a mixture of 5 sodium hydroxide and 95 calcium hydroxide. In a closed circuit, expired gas is passed through soda lime which completely absorbs carbon dioxide and the expired gas is then passed into a reservoir bag which is then reused. Absorbant should be changed when 50-70 has changed colour. 