Carnallite does not contain

Valency electrons in alkali metals are

Give any two uses of washing soda.

Assertion : $K$,$Rb$ and $Cs$ (all belonging to group $1$) can also form superoxides.
Reason : The ionic radii of $K$,$Rb$ and $Cs$ show the following trend $Cs^{+} < Rb^{+} < K^{+}$.

On heating 'Trona $(Na_2CO_3 \cdot NaHCO_3 \cdot 2H_2O)$' with the help of a Bunsen burner,we get . . . . . . as the solid residue.

Choose the compound of each of the following pairs that has the more solubility in water:
$(a) \, BeSO_4, BaSO_4$
$(b) \, NaCl, MgCl_2$
$(c) \, AgCl, AgI$