Answer
See explanation below.
Work Step by Step
Variation of ACID STRENGTH across a period :
Electronegativity increases as we go from left to right across any period in the Periodic table. And, as electronegativity increases, the acidity of the binary hydride also increases.
This is because, from left to right, as E becomes more electronegative, it withdraws electron density from H, and the EāH bond becomes more polar. As a result, H+ is pulled away more easily by an O atom of a water molecule.
In aqueous solution, the hydrides of Groups 3A(13) to 5A(15) do not behave as acids, but an increase in acid strength is seen from Group 6A(16) to 7A(17).