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Federal (FBISE) · Chapter test · Free

2nd Year Chemistry Chapter 17 Test17. Qualitative Analysis

30 marks · 40 minutes · 21 questions. Covers: 17. Qualitative Analysis.

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2nd Year Chemistry Chapter 17 Test

2nd Year · Chemistry · Federal (FBISE)

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

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

  1. Two peaks in the chlorine mass spectrum show that:
    1. Chlorine has one isotope
    2. Chlorine has two isotopes
    3. Chlorine is monoisotopic
    4. Chlorine is a mixture with hydrogen
  2. The isotope boron-11 has a relative abundance of:
    1. 0.199
    2. 0.11
    3. 0.801
    4. 0.9
  3. In the boron spectrum, the isotope with mass number 10 has what relative abundance?
    1. 0.801
    2. 0.5
    3. 0.199
    4. 0.1
  4. The M+2 peak in ethene is due to:
    1. Presence of two carbon-13 isotopes
    2. Presence of hydrogen isotopes
    3. Presence of oxygen isotopes
    4. Base peak splitting
  5. Mass spectrometry is mainly used to analyse:
    1. Atomic number
    2. Number of isotopes
    3. Boiling points
    4. Melting points
  6. The peak at m/z = 29 corresponds to:
    1. Ethyl cation
    2. Propyl cation
    3. Hydrogen radical
    4. Hydroxyl cation
  7. Average atomic mass of an element can be calculated by using:
    1. UV visible spectroscopy
    2. IR spectroscopy
    3. Mass spectrometry
    4. Nuclear magnetic resonance spectroscopy
  8. In the mass spectrum of ethene (C₂H₄), the molecular ion peak appears at:
    1. m/z = 25
    2. m/z = 28
    3. m/z = 29
    4. m/z = 30
  9. Structure can be recognized by:
    1. Molecular ion peak
    2. M+1 peak
    3. M+2 peak
    4. All peaks
  10. The two isotopes of bromine have relative abundances of approximately:
    1. 90% and 10%
    2. 75% and 25%
    3. 50.50% and 49.50%
    4. 24.23% and 75.77%

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

  1. How is the relative abundance of isotopes determined in mass spectrometry?
  2. Which cation corresponds to the peak at m/z = 15?
  3. Define base peak and explain its significance.
  4. How can you calculate average atomic mass of an element using relative abundances of all isotopes?
  5. State the mass numbers of the isotopes of boron.
  6. Why is the M+2 peak in ethene usually much smaller than M⁺ and M+1 peaks?
  7. At what m/z value does the molecular ion peak of chlorine appear?
  8. How can you identify the presence of chlorine and bromine in the molecule using mass spectrum?

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

  1. Analyse in detail, the information obtained by the fragmentation pattern in mass spectrum, used for the structural elucidation of a molecule.
  2. Describe the general uses of mass spectrometry in determining molecular masses, structure of organic molecules, and reaction mechanisms.
  3. Explain how the number of carbon atoms in a molecule can be calculated using molecular ion peak and M+1 peak intensities, with an example.