81.Consider the following statements : 1. Glycerol is used in explosives.2. Detergents are made from hydrocarbons obtained from coal or petroleum3. Sodium perborate is a mild bleaching agent.4. Methanol is used for making synthetic fibres. Which of the statements given above are correct ?

82.Consider the following statements : 1. Anthydrous sodium carbonate is commonly known as baking soda.2. Baking soda is used in fire extinguishers.3. Bleaching powder is manufactured in Hesenclever plant .Which of the statements given above is/are correct ?

83.Electron was first identified by :

84.Which of the following are the discoveries of Einsten ?

85.A silver spoon and a book are both at room temperature. The spoon feels colder to the touch because :