Q. Symbol of material used in conventional glass thermometers is

The correct answer is Option B: Hg.

Explanation: Conventional glass thermometers typically use mercury (symbol: Hg) as the material inside the thermometer. Mercury is a liquid metal at room temperature and has a high coefficient of expansion, making it ideal for accurately measuring temperature changes. It is also visible due to its shiny, metallic appearance, which makes it easy to read the temperature scale. Other options like Mg (magnesium), Me (not a valid chemical symbol), and Mn (manganese) are not used in conventional thermometers.