He used a 12 inch (30 cm) "burning lens" to focus the sun’s rays and heated mercuric oxide. He noticed that “a most remarkable gas was emitted”. In this gas he found that a candle burned ...

(a) Formation of slaked lime from quicklime. (b) Heating mercuric oxide. (c) Formation of manganese chloride from manganese oxide (MnO2). (d) Formation of zinc from zinc blende. (b) Mg gets oxidised.

“Button cell batteries (mercuric oxide, silver oxide, etc.) should not go in the trash. Instead, they should be recycled or taken to a household hazardous waste collection center.” That being ...