20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample?
(Atomic weight: Mg = 24)

Although chlorine is an electron withdrawing group, yet it is ortho- and para-directing in electrophilic aromatic substitution reaction because
(A) Chlorine withdraws electrons through inductive effect.
(B)Chlorine destabilises the intermediate carbocation formed during electrophilic substitution.
(C) Chlorine accepts electrons through resonance.
(D) Chlorine releases electrons through resonance.
Choose the correct answer from the options given below:

In Etard reaction, the final product is