Which ion is cyanide?

Which ion is cyanide?

• A. CNO-
• B. CN-
• C. NC-
• D. CN2-

Answer: (B)

Cyanide is the diatomic anion composed of one carbon and one nitrogen with a −1 charge, written as CN−. It has a strong C≡N bond and is the familiar ion found in salts like potassium cyanide. The option with CNO− is cyanate, a different species that includes oxygen and a different connectivity, so it’s not cyanide. Writing NC− would be just another way to spell the same two atoms, but the standard representation of cyanide is CN−, not NC−. The form CN2− would imply a completely different composition and charge, not cyanide. So the ion that corresponds to cyanide is CN−.

Cyanide is the diatomic anion composed of one carbon and one nitrogen with a −1 charge, written as CN−. It has a strong C≡N bond and is the familiar ion found in salts like potassium cyanide. The option with CNO− is cyanate, a different species that includes oxygen and a different connectivity, so it’s not cyanide. Writing NC− would be just another way to spell the same two atoms, but the standard representation of cyanide is CN−, not NC−. The form CN2− would imply a completely different composition and charge, not cyanide. So the ion that corresponds to cyanide is CN−.