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Punjab (PTB) · Chapter test · Free

1st Year Chemistry Chapter 9 TestAcid-Base Chemistry

30 marks · 40 minutes · 21 questions. Covers: CHAP 9: Acid-Base Chemistry.

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1st Year Chemistry Chapter 9 Test

1st Year · Chemistry · Punjab (PTB)

Name: ____________Roll No: ________Class/Section: ________Date: ________Total marks: 30Time: 40 minutes

Q1. Multiple choice questions (Attempt all · 10 × 1 = 10)

  1. The pH of 10-3mol dm-3 of an aqueous solution of H2SO4 is:

    1. 3.0

    2. 2.7

    3. 2.0

    4. 1.5

  2. A basic buffer solution can be prepared by mixing:

    1. Weak acid and its salt with strong base

    2. Strong acid and its salt with weak base

    3. Weak base and its salt with strong acid.

    4. Strong base and its slat with weak acid

  3. The ionic product of water will increase if:

    1. H+ ions are added,

    2. OH- ions are added

    3. Temperature is increased

    4. H+ and OH- ions are added in equal amount

  4. In a titration of a strong acid with a strong base, which indicator would be most suitable if the equivalence point is expected to be around pH 7?

    1. Phenolphthalein (pH range 8.2-10.0)

    2. Methyl orange (pH range 3.1-4.4)

    3. Bromothymol blue (pH range 6.0-7.6)

    4. Litmus (pH range 5.5 - 8.2)

  5. Which of the following species can act as a Lewis acid due to having an incomplete octet of electrons?

    1. H2O

    2. CH4

    3. BF3

    4. NH3

  6. When HCl is added to an aqueous solution of H2S its ionization:

    1. Increases

    2. Remains constant

    3. Decreases

    4. First decreases then increases

  7. Buffer action can be explained by:

    1. Common ion effect

    2. Law of mass action

    3. Le-Chatelier's Principle

    4. All above

  8. When HCl gas is passed through the solution of NaCl, sodium chloride is precipitated out, due to:

    1. Increasing solubility of NaCl

    2. Decrease in ionization of NaCl

    3. Increasing ionization of NaCl

    4. Formation of a complex

  9. What will be effect on solubility of PbCrO4 if some common ion is added to the given dynamic equilibrium: PbCrO4(s)  Pb2+(aq) + CrO42-(aq)

    1. Decreases

    2. Increases

    3. Remains same

    4. No effect

  10. The Negative log of the ionization constant of water is:

    1. pKw

    2. pKa

    3. pKb

    4. pH

Q2. Short questions (Attempt any 6 of 8 · 6 × 2 = 12)

  1. Why is the water molecule considered amphoteric according to the Bronsted-Lowry theory? Provide equations to illustrate its behavior as both an acid and a base.

  2. Explain the concept of a conjugate acid-base pair using a specific example.

  3. Define the following with an example for each:(i) Common ion effect (ii) Acid-base Indicator

  4. Write some applications of Buffer solutions.

  5. During the titration of a weak acid with a strong base. What will be the pH at the equivalence point to be acidic, basic, or neutral and what type of indicator would be most suitable for this titration?

  6. State the basic principle of solubility product. Mention factors affecting solubility product.

  7. Describe the difference between the endpoint of a titration and the equivalence point. How does the choice of indicator relate to this difference?

  8. Explain the concept of conjugate acid-base pairs. How are they related in terms of proton transfer?

Q3. Long questions (Attempt any 2 of 3 · 2 × 4 = 8)

  1. Derive the relation for the calculation of the ionization constant for acids.

  2. A buffer solution has a pH of 5.0. It is made from a weak acid HA with a pKa of 4.8. What is the ratio of the concentration of the conjugate base [A-] to the concentration of the weak acid [HA] in this buffer?

  3. The molar solubility of silver chromate (Ag2 CrO4) in pure water at 298 K is 6.5×10-5 mol dm-3. Calculate the Ksp of silver chromate at this temperature.