Question

Write the chemical formulae and names of the compounds formed by the following ions:

(i) Cr³⁺ and SO₄^2– (ii) Pb²⁺ and NO₃^– (iii) Mg²⁺ and CO₃^2–

Answer 1

(i) Cr³⁺ and SO₄^2- 

By applying criss-cross method:

Chemical formula: Cr₂(SO₄)₃ 

Name of the compound: Chromium sulphate

(ii) Pb²⁺ and NO₃^–

By applying criss-cross method:

Chemical formula: Pb(NO₃)

Name of the compound: Lead nitrate 

(iii) Mg²⁺ and CO₃^2–

By applying criss-cross method:

Chemical formula: MgCO₃ 

Name of the compound: Magnesium carbonate