NaH < H2S < H2Te < HI in NaH there is one hydrogen atom which is present as H- so it is a base. now in Oxygen group Te is below S so the acidity is greater for H2Te than H2S and because of the higher electronegativity and the larger size HI has the highest acidity among the given compounds. Solution NaH < H2S < H2Te < HI in NaH there is one hydrogen atom which is present as H- so it is a base. now in Oxygen group Te is below S so the acidity is greater for H2Te than H2S and because of the higher electronegativity and the larger size HI has the highest acidity among the given compounds..