In India,at the occasion of marriages,the fireworks used give a green flame. Which one of the following radicals may be present?

Lime reacts exothermally with water to give '$A$' which has low solubility in water. Aqueous solution of '$A$' is often used for the test of $CO_{2}$,a test in which insoluble $B$ is formed. If $B$ is further reacted with $CO_{2}$ then a soluble compound is formed. '$A$' is

Which of the following reactions does not take place?

Chemical $A$ is used for the removal of temporary hardness of water. Compound $A$ reacts with $Na_2CO_3$ to produce caustic soda. When $CO_2$ gas is passed through $A$,it turns milky. What is the chemical formula of $A$?

What is the difference in the number of water molecules between gypsum and plaster of Paris?

Which of the following chlorides is covalent and soluble in ether?