Which is not dissolved in dil. HCl?

To a clear solution os compound (X), a solution of BaCl_(2) added and a heavy white precipitate is formed which does not dissolve in dil, HCl. The compound (X) is

Which of the following compounds is not dissolved in dil. HNO_(3) ?

Which out of the following does not dissolve in dilute HCl ?

Three black powder A,B,D are kept in three dishes. A dissolves in dil H_(2)SO_(4) to give blue solution. Moistened with HCl, A gives a green colour in flame test. B does not dissolve in dil HCl but when boiled with concentrated HCl, dissolves giving chlorine. This solution with H_(2)S in ammonical solution produces a flesh coloured precipitate C does not dissolve in HCl but when heated with KNO_(3) , burns away evolving a gas which lime water milky. What are A,B, & C ?

An element 'A' reacts with oxygen to form an oxide of the formula A_2O which dissolves in dil. HCl. The oxide formed turns red litmus paper blue. Is the element a metal or a non-metal?

An element 'A' reacts with oxygen to form an oxide of the formula A_2O which dissolves in dil. HCl. The oxide formed turns red litmus paper blue. Write the formula of A_2O and its reaction with dil. HCl.

The compound which is insoluble in dil. HCl is:

Why Cu does not dissolve in HCl.