The product obtained on fusion of $BaSO_4$ and $Na_2CO_3$ is

Which of the following produces hydrolith with dihydrogen?

Dead burnt plaster is

Addition of an oxalate solution to an aqueous solution containing a mixture of $Ba^{2+}$,$Sr^{2+}$,and $Ca^{2+}$ ions will precipitate:

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$ :
Assertion $(A)$ : $BeCl_2$ and $MgCl_2$ produce characteristic flame.
Reason $(R)$ : The excitation energy is high in $BeCl_2$ and $MgCl_2$.
In the light of the above statements,choose the correct answer from the option given below :

Mortar is a mixture of