What is the colour of the precipitate obtained by passing CO₂ gas through lime water?

When air is blown from mouth into a test tube containing limewater, the limewater turns milky. This is due to the presence of

Which one of the following materials is present in a guard tube (drying tube) that is used for preparation of HCl gas?

Calcium oxide reacts vigorously with water to produce slaked lime whose solution is used for white-washing walls. This slaked lime reacts with component (A) in air to form a thin layer of component (…

When we heat lead nitrate [P(NO₃)₂] in a boiling tube, we observe the emission of brown fumes. Which one of the following is the brown gas?

Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour ?