An ungraduated mercury thermometer attached to a millimeter scale reads 22.8 millimeter in ice and 242m in steam at standard pressure. What will be the millimeter when the temperature read 20 °c.

An ungraduated mercury thermometer attached to a millimeter scale reads 22.8 millimeter in ice and 242m in steam at standard pressure. What will be the millimeter when the temperature read 20 °c.