Which of the following species is a radical? A. CN− B. NO C. NO3− D. KrF+ E. SF6

To determine which of the given species is a radical, we need to define what a radical is. A radical is a species that has an unpaired electron, making it highly reactive.

Let's analyze each option:

1. CN− (Cyanide ion): This species has a complete octet for carbon and nitrogen, with no unpaired electrons. So, it is not a radical.

2. NO (Nitric oxide): This molecule has an unpaired electron on the nitrogen atom, making it a radical.

3. NO3− (Nitrate ion): This species is also stable with all electrons paired, as it has resonance structures that distribute its charge.

4. KrF+ (Krypton fluoride cation): Krypton is a noble gas and generally does not form radicals. In this species, all electrons are paired.

5. SF6 (Sulfur hexafluoride): This is a stable compound with all paired electrons around sulfur, thus not a radical.

Final Answer

The radical species from the given options is B. NO (Nitric oxide).