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  • Question
  • Which one of the following elements cannot be detected by "Lassaigne's test"?


  • Options
  • A. I
  • B. Cl
  • C. S
  • D. F

  • Correct Answer


  • Explanation

    The sodium fusion test, or Lassaigne's test, is used in elemental analysis for the qualitative determination of the presence of foreign elements, namely halogens, nitrogen, and sulphur, in an organic compound. It was developed by J. L. Lassaigne.Silver fluoride is soluble in water and does not precipitate and thus this method cannot be used for detection of fluorine.

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    Chemistry problems


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    • 1. Match List -I with List -II and select the correct answer using the code given below the Lists : List -I List-II (Compound/Molecule) (Shape of Molecule) A. CH3F 1. Trigonal planar B. HCHO 2. Tetrahedral C. HCN 3. Trigonal pyramidal D. NH3 4. Linear

    • Options
    • A. 2 4 1 3
    • B. 2 1 4 3
    • C. 3 4 1 2
    • D. 3 1 4 2
    • Discuss
    • 2. Which one of the following statements is correct?

    • Options
    • A. The oxidation number for hydrogen is always zero.
    • B. The oxidation number for hydrogen is always + 1.
    • C. The oxidation number for hydrogen is always -1.
    • D. Hydrogen can have more than one oxidation number.
    • Discuss
    • 3. Highest percentage of carbon is found in which form of coal?

    • Options
    • A. Anthracite
    • B. Bituminous
    • C. Peat
    • D. lignite
    • Discuss
    • 4. Which one of the following elements does not form solid hydrogen carbonate?

    • Options
    • A. Sodium
    • B. Potassium
    • C. Caesium
    • D. Lithium
    • Discuss
    • 5. Bee sting contains________________

    • Options
    • A. An acidic liquid
    • B. a salt solution
    • C. an alkaline liquid
    • D. a corrosive liquid
    • Discuss
    • 6. In which of the following, functional group isomerism is not possible?

    • Options
    • A. Alcohols
    • B. Aldehydes
    • C. Alkyl halides
    • D. Cyanides
    • Discuss
    • 7. Which one of the following statements is not correct?

    • Options
    • A. Fischer projection represents the molecule in an eclipsed conformation
    • B. Newman projection can be represented in eclipsed, staggered and skew conformations
    • C. Fischer projection of the molecule is its most stable conformation
    • D. In Sawhorse projections, the lines are inclined at an angle of 120 deg to each other.
    • Discuss
    • 8. Which of the following is most important for absorption of heat radiated from the Sun as well as from the Earth?

    • Options
    • A. Carbon dioxide
    • B. Oxygen
    • C. Carbon monoxide
    • D. Nitrogen
    • Discuss
    • 9. What are isobars?

    • Options
    • A. Elements with same atomic number but different mass number
    • B. Elements with different atomic number but same mass number
    • C. Elements with different atomic number and different mass number
    • D. Elements with same atomic number and same mass number
    • Discuss
    • 10. Which of the following pairs is INCORRECT? I. Haematite : Iron II. Pitchblende : Copper III. Monazite : Thorium

    • Options
    • A. Only I
    • B. Only II
    • C. Only I and Only II
    • D. Only I and Only III
    • Discuss


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