Identify the incorrect statements.

1. Polonium is radioactive.
2. H₂S is more acidic than H₂Te.
3. Ozone is thermodynamically more stable with respect to oxygen.
4. Phosphine is used in Holme’s signals.

Select the correct answer using codes given below:

H₂S is less acidic than H₂Te. Due to the decrease in bond (E–H) dissociation enthalpy down the group, acidic character increases. Ozone is thermodynamically unstable with respect to oxygen since its decomposition into oxygen results in the liberation of heat (∆H is negative) and an increase in entropy (∆S is positive). These two effects reinforce each other, resulting in large negative Gibbs energy change (∆G) for its conversion into oxygen.