We will find fine microscopic sulphur particles precipitating in about 2 and 3 minutes due to the reaction between sulphuric acid sodium thiosulphate.

Out of the given four materials the refractive index of glycerine is highest. So, greatest deviation of incident light ray is observed in case of glycerine.

As MnO₂ reacts with HCl to form salt, water and chlorine gas, it is basic oxide since it reacts with an acid. Moreover, oxides of metal are basic in nature whereas oxides of non-metals are acidic in nature.

Autotrophs take in food from the outside world and convert them into stored forms of energy. This material is taken in the form of carbon dioxide and water which is converted into carbohydrates in the presence of sunlight and chlorophyll.

Metals generally do not show dullness. Metals such as gold and silver are usually shiny rather than dull.