Question

7) A buffer solution is formed by adding 0.0100 moles of potassium dihydrogen phosphate (KH2PO4) and 0.0100 moles of potassium hydrogen phosphate (K_HPO4) into 1.000 liters of water. When 0.0010 moles of NaOH is added to this solution, what will happen? a) The pH of the solution will increase by a small amount (< 0.10 pH units) b) The pH of the solution will increase by a large amount > 0.10 pH units) c) The pH of the solution will be exactly the same as before the addition of the NaOH d) The pH of the solution will decrease by a small amount (<0.10 pH units) e) The pH of the solution will decrease by a large amount (> 0.10 pH units) 8) For the chemical reaction NH3(aq) + HCl(aq) + NH4+ (aq) + CF(aq) the acid and conjugate base are a) HCl (acid); C(conjugate base) b) HCl (acid); NH3 (conjugate base) c) HCI (acid); NH4+ (conjugate base) d) NH3 (acid); NH4+ (conjugate base) e) NH3 (acid); CI (conjugate base) 9) For which of the following substances does phosphorus (P) have the largest value for oxidation number? a) NazP b) H3PO4 c) PF3 d) P4 e) PO33- 10) Which of the following is always true for the oxidation numbers in an oxidation-reduction reaction? a) The value for the oxidation number for atoms of the element being oxidized must increase as we go from reactants to products b) The initial value for the oxidation number for atoms of the element being oxidized must be positive c) The final value for the oxidation number for atoms of the element being oxidized must be positive d) Both b and c e) None of the above is always true 11) In the Arrhenius equation, the value for A, the pre-exponential factor, depends on a) the activation energy (the minimum energy needed to convert reactants into products) b) the collision frequency (number of collisions per unit volume and unit time) c) the orientation factor (the fraction of collisions that have an orientation favorable for reaction to occur) d) Both b and c e) Both a and b and c 12) Which of the following is true of a catalyst? a) A catalyst is a substance b) A catalyst, when added to a reaction system, increases the rate at which the reaction occurs c) A catalyst is neither produced nor consumed as a reaction proceeds d) Both b and c e) Both a and b and

Answer 1

7. As NaOH is base the pH will increase but as it is a buffer solution the pH increase will resist thus it will increase slightly. opt a is correct.

8. Here HCl is the acid so it's conjugate base must be Cl-. So, opt a is correct.

9. The correct opt is b as here P is in +5 state(highest).

10. opt a is correct as oxidation no increases as electron is eliminated.

11. The correct opt is d as both b and c is correct.

12. The correct opt is e as all a,b,c are correct.