is hcn a strong acid?
HCN, also known as hydrocyanic acid or prussic acid, is a weak acid. ... Memorize the short list of acids that are typically thought of as strong. This includes HCl, HBr, HI, HNO3, HClO3, HClO4, and H2SO4. If an acid doesn't appear on this list, it is not considered to be strong.