Midterm Review Worksheet Doubts

[Ananya Ravikumar 1I]

These are from Adila's midterm 1 review worksheet. I cannot make her step-up sessions so I wanted to know how everyone answered the questions:

A chemical equilibrium may be established by starting a reaction with _______
a. Reactants only
b. Products only
c. Equal quantities of reactants and products
d. Any quantities of reactants and products
e. All of the above

and

Selenious acid, H2SeO3, has ionization constants of Ka1 = 3 x 10-3 and Ka2 = 5 x 10-8. Determine the following for a 0.50M solution:
a. Calculate the concentration of all species in the solution (should have 5 species)
b. Calculate the pH and pOH

Thank you!

[Natasha Sutkin 2B]

For the first question it would be E. All of the above because the equilibrium concentrations ratio is not affected by how much and what is originally in the reaction.

For the second question, for most polyprotic acids you just use the first Ka value to determine pH and pOH so I would assume you'd do the same for Selenious Acid.