When HCl is added to metal ions, metal chlorides are produced. In this problem, it is asked whether the given ions precipitate or not when added to HCl. According to the rule, all chlorides except Ag+, Pb 2+, Hg2 2+ are soluble. Hence the ion that would precipitate is only lead (II) ion.
Answer::Democritus
Explanation
The idea that all matter is made up of tiny, indivisible particles, or atoms, is believed to have originated with the Greek philosopher Leucippus of Miletus and his student Democritus of Abdera in the 5th century B.C. (The word atom comes from the Greek word atomos, which means “indivisible.”) These thinkers held that,
<span>The purpose of washing the product with NaOH is simply to
neutralize any acid which remained or leaked after the 1st initial
separation. The NaOH base reacts with the acid to form neutralization reaction products
which are soluble in water.</span>
