Which group 16 hydrides are toxic gases with strong odors?

The group 16 hydrides that are toxic gases with strong, repulsive odors are hydrogen sulfide ($H_{2}S$), hydrogen selenide ($H_{2}Se$), and hydrogen telluride ($H_{2}Te$).1

While water ($H_{2}O$) is also a group 16 hydride, it is not a toxic gas with a strong odor; its properties are distinct due to hydrogen bonding, which keeps it in a liquid state at ambient conditions. In contrast, the other dihydrides in this group are volatile, poisonous compounds. Hydrogen sulfide is well known for its characteristic odor of rotten eggs, while hydrogen selenide is noted for having a disagreeable smell similar to that of hydrogen sulfide. These compounds are easily prepared by reacting dilute acids with their corresponding metal sulfide, selenide, or telluride.123