Which of the following is true about anesthesia machine

A i.e. Desflurane vapourizer is heated to 39degC Rotameter is constant pressure, variable orifice (area) flow meter for gases and liquid bothQ. - Halothane vaporizes at 50.2degC (ie boiling point) -O2 sensor can be attached both on expiratory and inspiratory limb of circle system's breathing circuit but not into the fresh gas line of machineQ. Desflurane's vaporizer are externally heated to 39degC to compensate for significant heat loss a/w desflurane vaporization. It also increases the vapour pressure (to 1300 mmHg), preventing the possibility of boiling in warm rooms. Tech 6 vaporizer is used only with desflurane. Desflurane is heated to 39degC (102degF)Q, which is well above its boiling point (22.8degC), by two heaters in the base. An external heating is needed, because the potency of desflurane requires that large amount be vaporized. And also because the boiling point of desflurane is near room temperature and depending on ambient temperature would make the output unpredictable. These factors make thermo compensation using the usual mechanical devices impossible.