The question is incomplete, the complete question is;
Enter the chemical formula of a binary molecular compound of hydrogen and a Group 6A element that can reasonably be expected to be more acidic in aqueous solution than H2S , e.g. have a larger Ka.
Answer:
H2Se
Step-by-step explanation:
The acidity and extent of acid dissociation (shown by Ka value) depends on the nature of the bond between hydrogen and the group 6A element.
If we compare the H-S bond and the H-Se bond, we will discover that the H-Se bond is longer, weaker and breaks more easily than the H-S bond. As a result of this, H2Se is more acidic than H2S.