Milk of lime is

An alkaline earth metal $M$ readily forms water-soluble sulphate and water-insoluble hydroxide. Its oxide $MO$ is very stable to heat and does not have rock-salt structure. $M$ is :-

The thermal stability of $MCO_3$ (where $M$ is an alkaline earth metal) follows the order:

Which one of the following alkaline earth metals does not form hydride when it is heated with hydrogen directly?

Which of the following is not correct?

Among the following,the basic oxide is .....