Answer the questions.

See explanation and images attached

Explanation:

The equation for the laboratory preparation of nitrogen is:

NH4Cl(aq) + NaNO2(aq) → N2(g) + 2H2O(l) + NaCl (aq).

When concentrated sulphuric acid is used, the nitrogen gas is oxidized to ammonia

N2(g) + 3H2(g) -----> 2NH3(g)

2Na(s) + 2H2O(l) -----> 2NaOH(aq) + H2(g) NOTE HERE THAT THE SECOND PRODUCT IN THIS REACTION IS HYDROGEN GAS AND NOT WATER AS WRITTEN IN THE WORD EQUATION.

Molecular formula of calcium phosphate is Ca3(PO4)2

Molecular formula of sodium bicarbonate is NaHCO3

In the duplet state, the outermost shell of an atom contains only two electrons e.g helium.

Octet state means that the outermost shell of the atom contains eight electrons as in the noble gases Ne, Ar, Kr etc

The equation for the laboratory preparation of oxygen is ;

2KClO3(s)----> 2KCl(s) + 3O2(g)

Finally, if an element burns in air to give a soluble oxide which turns red litmus blue (basic property) then the element is a metal. Metals form basic oxides which dissolve in water to form alkaline solutions which turns red litmus paper blue.