Question

Brass gets discoloured in air due to

constant exposure in presence of:

A. Aluminium phosphide

B. Hydrogen sulphide

C. Hydrogenated wafers

D. Aluminium Sulphide​

Answer 1

Ans. B

Sol. The normal brown coloration on

brass which slowly forms is

primarily due to the oxidation of the

copper (which makes up about 70%

or more of the Brass alloy) to

copper oxide. The greenish patina

that forms on brass (especially in

inclement environments) can be a

complex of copper carbonates and

acetates (acetates come from

naturally or artificially occurring

contaminants or droppings in the

atmosphere depending on the

presence of Industry).