General Knowledge - General Science - Discussion

It is one of the nature.

This is called Tarnishing. It is a thin layer of corrosion that forms over copper, brass, silver, aluminium, magnesium and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish, although it may tarnish with oxygen over time. It often appears as a dull, grey or black film or coating over metal. Tarnish is a surface phenomenon that is self-limiting, unlike rust. Only the top few layers of the metal react, and the layer of tarnish seals and protects the underlying layers from reacting the tarnishing.

Brass is the alloy of Copper & Zinc.

Brass reacting with Hydrogen Sulphate present in the atmosphere it forms Zinc Sulphate.

Why can't (D) be the answer? Explain please.

I think option B is right.

Because it performs bleaching action probably.I'm not sure however!!

Why cant other can perform it?

Because of chemical reaction.

It is because the presence of mixture of hydrogen and sulphide and brass is a type of thing which has a color very light and mixture is non temperature (hot and cold type of temperature) so it gets discolored.this is better answer.etc

I think that option a is correct because O2 can react with brass and can discolored it