In which of the following triatomic molecules or ions are both of the bonds multiple bonds?

HCN

CO2

NO2

more than one correct response

no correct response

If more than one correct response then please show all the correct answers.

thanks

HCN no

CO2 yes
NO2 probably if you count the resonance structures as being partially multibonding.

To determine which of the given triatomic molecules or ions have multiple bonds, we need to identify the Lewis structures and count the number of bonds between the atoms.

1. HCN: The Lewis structure for HCN would have a single bond between the hydrogen (H) and the carbon (C) atoms, and a triple bond between the carbon (C) and nitrogen (N) atoms. So, in HCN, both bonds are multiple bonds.

2. CO2: The Lewis structure for CO2 would have double bonds between the carbon (C) atom and each oxygen (O) atom. However, CO2 is not a triatomic molecule or ion since it only consists of two atoms (carbon and oxygen).

3. NO2: The Lewis structure for NO2 would have a single bond between the nitrogen (N) and one oxygen (O) atom, and a double bond between the nitrogen (N) and the other oxygen (O) atom. So, in NO2, only one bond is a multiple bond.

Therefore, the correct response is:
- HCN: Both bonds are multiple bonds.

Hence, the answer is "HCN".