Final answer:
The decreasing acidity order is HClO3 > H3PO4 > CH3PO3 H2, based on electronegativity and resonance, while the increasing base strength order is CF3S¯ < CH3S¯ < OH¯, considering the electron-withdrawing effects and electronegativity.
Step-by-step explanation:
To answer the student's question on the order of decreasing acidity of the molecules: H3PO4, CH3PO3 H2, and HClO3, one must consider factors such as the stability of the conjugate base, electronegativity, and resonance. Comparing these acids, HClO3 is the strongest acid followed by H3PO4, and then CH3PO3 H2 is the weakest. The high electronegativity of chlorine in HClO3 and its ability to stabilize the negative charge through resonance makes it the strongest acid among these.
Regarding the order of increasing base strength among CH3S¯, OH¯, and CF3S¯, the least basic is CF3S¯ due to the electron-withdrawing effect of the three fluorine atoms, which diminishes the ability of sulfur to donate its lone pair. OH¯ is more basic than CH3S¯, due to oxygen being more electronegative than sulfur, thus more willing to share its electron pair.