Question

copper and brass vessels are cleaned with lemon

Answer 1

Copper and brass vessels are cleaned with lemon because lemon contains citric acid and non metals are electron gainers so it cannot produce hydrogen gas when react with acid there for non metals do not react with acid so that's why Copper and brass vessels are cleaned with lemon.

Answer 2

$\huge\star\mathfrak\red{{Hey Mate...!!}}$

Ans: The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer. That is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.