Question

Which is the correct thermal stability order for $H_{2}E$
$(E=O,S,Se,TeandPo)$ ?

• A. $H_{2}Po<H_{2}Te<H_{2}Se<H_{2}S<H_{2}O$
• B. $H_{2}Se<H_{2}Te<H_{2}Po<H_{2}O<H_{2}S$
• C. $H_{2}S<H_{2}O<H_{2}Se<H_{2}Te<H_{2}Po$
• D. $H_{2}O<H_{2}S<H_{2}Se<H_{2}Te<H_{2}Po$

Answer 1

The correct option is A $H_{2}Po<H_{2}Te<H_{2}Se<H_{2}S<H_{2}O$

On going down the group, thermal stability order for $H_{2}E$ decreases because $H-E$ bond energy decreases.
Hence, order of stability would be:
$H_{2}Po<H_{2}Te<H_{2}Se<H_{2}S<H_{2}O$