2- A 0.310 M solution of a weak acid, HX, has a pH of 2.53

Question

a. Find the [H+] and the percent ionization of nitrous acid in this solution.
b. Write the equilibrium expression and calculate the value of Ka for the weak acid.
c. Calculate the pH of the solution formed by adding 10 g of KX (molar mass = 59.0 g•mol–1) to 650 mL of 0.0125 M solution of the weak acid.
d. Determine the pH of a solution formed by adding 10 g of KX to 750 mL of water.

Answer 1

I'm confused by the question. Is HX in the preamble the same as HNO2 is part a or is that different?

Answer 2

What is the molarity of a solution prepared by dissolving 4.92 g of calcium nitrate in 250 mL of water?

4.92 x 164 = 806.88

806.88 x 250 =201720

is this the answer???