From which of the following minerals is $Ra$ (Radium) obtained?

Which of the following is the correct increasing order for the mentioned property?

Lithium nitrate on heating gives

On heating to $400-500\,^oC$,relatively unstable hydrides and carbonates decompose. Which of the following will decompose when heated to $400-500\,^oC$ ?
$(I) \ LiH$ $ $ $(II) \ NaH$ $ $ $(III) \ Li_2CO_3$ $ $ $(IV) \ Na_2CO_3$

Select the correct statement.

Calcium is obtained by