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Punjab (PTB) · Chapter test · Free

2nd Year Chemistry Chapter 13 TestSPECTROSCOPY-1

28 marks · 40 minutes · 19 questions. Covers: CHAP 29: SPECTROSCOPY-1.

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2nd Year Chemistry Chapter 13 Test

2nd Year · Chemistry · Punjab (PTB)

Name: ____________Roll No: ________Class/Section: ________Date: ________Total marks: 28Time: 40 minutes

Q1. Multiple choice questions (Attempt all · 8 × 1 = 8)

  1. The average atomic mass of Ne having isotopes , with natural abundance is:

    1. 20.50 amu

    2. 20.18 amu

    3. 30.70 amu

    4. 20.00 amu

  2. Which of the following fragments will not be produced in the fragmentation of hexane ?

    2. M + 1

    3. M - 1

    4. M + 4

  3. Which of the following compounds can produce the IR spectrum shown below? image

    1. Propanoic acid

    2. 4-hydroxybutanone

    3. Pentan-1-ol

    4. 2-hydroxybut-1-ene

  4. The of to  transitions lies in the: 

    1. IR region

    2. Visible region

    3. UV region

    4. None of the above

  5. Which of the following statements about the mass spectrum of CH3Cl is correct?

    1. There is one peak for the molecular ion with an m/e value of 45

    2. There is one peak for the molecular ion with an m/e value of 52

    3. The last two peaks have abundances in the ratio 3:1 and occur at m/e values of 50 and 52

    4. The last two peaks are of equal size and occur at m/e values of 50 and 52

  6. The IR spectrum of a compound X contains peaks at 1560 1690 and a broad peak between 2500-- 3200, Thus X is most likely:

    1. An unsaturated ketone

    2. An alkene

    3. An unsaturated carboxylic acid

    4. An alcohol

  7. The types of transitions possible in UV-visible region for a compound with molecular formula C4H8 are:

  8. What is the wavelength range of the UV-Vis spectrum?

    1. 100 nm to 500 nm

    2. 200 nm to 800 nm

    3. 300 nm to 1000 nm

    4. 400 nm to 1600 nm

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

  1. The molecular formulas of the following compounds are given below: but-1-ene: C4H8 buta-1,3-diene: C4H6: Find out the IHD of both of these compounds.

  2. Explain how the two isomers shown in the diagram can be distinguished using the IR spectroscopy. image

  3. How will you differentiate between the following using the UV visible spectroscopy. image

  4. Identify the functional groups responsible for the peaks labelled X and Y. image

  5. Compound X is an atmospheric pollutant emitted from combustion of petrol and diesel vehicles. Compound X is a potent human carcinogen. Analysis of compound X showed the following percentage composition by mass: C, 88.89% and H, 11.1%. Mass spectrometry showed a molecular ion peak at m/e = 54. Compound X reacts with H2 in the presence of a nickel catalyst in a 1: 2 molar ratio. Analyse and interpret this information to determine a possible structure for compound X. Show all your working.

  6. Bromobutane, , can be reacted with hot aqueous sodium hydroxide to prepare butan-1-ol. Butan-1-ol produced can be analysed by mass spectrometry. Predict the formula of the fragment ion with a m/e value of 17.

  7. Bromobutane, can be reacted with hot aqueous sodium hydroxide to prepare butan-1-ol. Butan-1-ol produced can be analysed by mass spectrometry.Predict two other fragment ions that you would expect to see in the mass spectrum of butan-1-ol and state the m/e value of each ion.

  8. Show all the possible fragments of C7H16 and their (m/e) values in its mass spectrum.

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

  1. How mass spectrometry is used to determine the isotopic mass and average atomic masses of elements? Explain giving an example.

  2. Explain two types of atomic spectrum.

  3. Describe various possible electronic transitions in a compound having sigma, pi bonds, and non-bonding electrons.