Identify the hydroxide which is soluble in excess of NaOH

Q. The hydroxide, which is soluble in excess of sodium hydroxide is:

Q. The metal hydroxide which is soluble in excess of ammonium hydroxide:

Q. The hydroxide which is soluble in excess of $NaOH$ is :

Q. A metal salt (M) on reacting with sodium hydroxide forms sodium sulphate and a gelatinous white precipitate of a metal hydroxide. The precipitate is soluble in excess of sodium hydroxide. Identify M.