Why on dilution the A of CH,COOH increasesdrastically, while that of CH,COONa increasesgradually?

It seems like there's a bit of confusion in your question, but I'll try to address what I think you're asking about - the behavior of acetic acid (CH3COOH) and sodium acetate (CH3COONa) upon dilution.

1. Acetic acid (CH3COOH) is a weak acid. This means it does not completely ionize in water. When you dilute acetic acid, you're adding more water molecules. These extra water molecules can interact with the acetic acid molecules, encouraging them to ionize and release more H+ ions. This increases the acidity (or decreases the pH), which could be what you're referring to with "A" (acidity).

2. Sodium acetate (CH3COONa) is a salt of a weak acid (acetic acid) and a strong base (sodium hydroxide). When you dissolve sodium acetate in water, it completely ionizes to form acetate ions (CH3COO-) and sodium ions (Na+). The acetate ions can react with water to form acetic acid and hydroxide ions (OH-), but this reaction is not favored. When you dilute the solution, you're adding more water, but this doesn't significantly change the concentration of acetate ions, so the pH (or "A") increases only slightly.

I hope this helps! Let me know if you have any other questions.