How are hydrogen sulfide, hydrogen selenide, and hydrogen telluride prepared?

Hydrogen sulfide ($H_{2}S$), hydrogen selenide ($H_{2}Se$), and hydrogen telluride ($H_{2}Te$) are all volatile, toxic gases that belong to the group 16 covalent hydrides.

These compounds are easily prepared by adding dilute acid to their corresponding metal sulfide, selenide, or telluride salts. For example, hydrogen selenide is typically formed through the action of acids on metal selenides.12

As you move down the periodic table within this group, the bond strength between the nonmetal and hydrogen decreases, which directly correlates to an increase in both the acidity of these compounds in water and their general chemical reactivity.1