NCERT MCQ Questions for Class 11 Chemistry Chapter with Answers PDF free download. MCQ Questions for Class 11 Chemistry with Answers were prepared based on the latest exam pattern. Class 11 chemistry MCQs with answers are provided here for Hydrocarbons. These MCQs are based on the CBSE board curriculum and correspond to the most recent Class 11 chemistry syllabus.
Class 11 chemistry chapter Hydrocarbon MCQs with Answer
Q1. Homolyte fission leads to formation of:
- Nucleophile.
- Carbanion.
- Free radical.
- Arbocation.
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Q3. The fragrance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are
generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for
the extraction of these oils from the flowers is:
- Distillation.
- Crystallisation.
- Distillation under reduced pressure.
- Steam distillation.
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Ans: 4. Steam distillation.
Explanation:
Essential oils are insoluble in water, soluble in steam and have high vapour pressure. Therefore, they can be separated by steam distillation.
Q4. Which type of bond is formed between carbon atom and nitrogen atom?
- Covalent bond.
- Ionic bond.
- Dative bond.
- None of these
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Ans: 1. Covalent bond.
Explanation:
A covalent bond is formed between carbon and nitrogen atom. If duplet (2) or octet (8) is completed by sharing of electrons between two
electronegative elements, the bond formed is called covalent bond.
Q5. The IUPAC name of iso-octane is:
- 2, 2-dimethylpentane.
- 2, 3-dimethylpentane.
- 2, 3, 3-trimethylpentane.
- 2, 2, 4-trimethylpentane
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Ans: 4. 2, 2, 4-trimethylpentane.
Q6. What is the name of tube in which a known mass of an organic compound is heated for the quantitative analysis of sulphur?
- Borosil tube.
- Carius tube.
- Kjeldahl tube.
- None of these.
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Ans: 2. Carius tube.
Explanation:
Tube in which a known mass of an organic compound is heated for the quantitative analysis of S is known as Carius tube.
Q7. Which of the following compounds will exhibit geometrical isomerism?
- 1-phenyl-2-butene.
- 3-phenyl-1-butene.
- 2-phenyl-1-butene.
- 1, 1-diphenyl-1-propane.
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Ans: 1. 1-phenyl-2-butene.
Q8. Which of the following method is used to purify liquids having very high boiling points and those which decompose at or
below their boiling points?
- Simple distillation.
- Fractional distillation.
- Distillation under reduced pressure.
- None of the above.
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Ans: 3. Distillation under reduced pressure.
Explanation:
Distillation under reduced pressure method is used to purify liquids having very high boiling points and those, which decompose at or below their
boiling points. Such liquids are made to boil at a temperature lower than their normal boiling points by reducing the pressure on their surface. A
liquid boils at a temperature at which its vapour pressure is equal to the external pressure. The pressure is reduced with the help of a water pump
or vacuum pump.
Q9.
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Q10.
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Q11. In which of the following ways the structure(s) of organic compounds is/ are represented?
- Lewis or dot structure.
- Dash structure.
- Condensed and bond-line structure.
- All of the above.
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Ans: 4. All of the above.
Q12. Look at the figure below and find the hybridisation of carbon atom.
Image
- sp3
- sp2
- sp
- None of these.
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Ans: 2. sp2
Q13. The technique in which extraction of compound takes place on the basis of more solubility of one compound in another
solvent, is:
- Differential extraction.
- Chromatography.
- Sublimation.
- Crystallisation.
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Ans: 1. Differential extraction.
Q14. For the purification, isolation and separation of organic compounds, the latest technique is:
- Chromatography.
- Steam distillation.
- Fractional crystallization.
- Sublimation.
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Ans: 1. Chromatography.
Q15. Which techniques is based on the difference in the solubilities of the compound and the impurities in a suitable solvent?
- Sublimation.
- Crystallisation.
- Distillation.
- None of these.
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Ans: 2. Crystallisation.
Explanation:
Crystallisation process is based on the difference in the solubilities of the compound and the impurities in a suitable solvent. The impure
compound is dissolved in a solvent in which it is sparingly soluble at room temperature but appreciably soluble at higher temperature.
Q16. Which of the following best describe the given statement “an atom or group of atoms joined in a specific manner which is
responsible for the characteristic chemical properties of the organic compounds?
- Heteroatom.
- Functional group.
- Aromatic group.
- Non-aromatic group.
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Ans: 2. Functional group.
Q17. In paper chromatography, chromatography paper contains water trapped in it, which acts as the:
- Mobile phase.
- Stationary phase.
- Stationary medium.
- None of these.
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Ans: 2. Stationary phase.
Explanation:
In paper chromatography, chromatography paper contains water trapped in it, which acts as the stationary phase.
Q18.In Duma’s method for estimation of nitrogen, 0.3g of an organic compound gave 50 mL of nitrogen collected at 300K
temperature and 715 mm pressure. The percentage composition of nitrogen in the compound (Aqueous tension at 300K =
15mm) is:
- 15.46%
- 17.46%
- 18.36%
- 28%
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Ans: 2. 17.46%
Q19. Glycerol is purified by:
- Vacuum distillation.
- Simple distillation.
- Steam distillation.
- Fractional distillation.
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Ans: 1. Vacuum distillation.
Explanation:
Because glycerol decomposes at its normal boiling point.
Q20
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Q21. The elements always present in organic compounds are C and H. In addition to these, name the other elements that may be
present in it:
- Oxygen and nitrogen.
- Sulphur and halogens.
- Phosphorus.
- All of these.
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Q22. During the fusion of an organic compound with sodium metal, nitrogen of the organic compound is converted into:
- NaNO2
- NaNH2
- NaCN
- NaNC
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Ans: 3. NaCN
Q23. Acidified sodium fusion extract on addition of ferric chloride solution gives blood red colouration. This confirms the presence
of which of the following element(s)?
- Both S and cl.
- Both N and S.
- Only N.
- Only S
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Ans: 2. Both N and S
Q24. Which of the following is the correct IUPAC name?
- 3-Ethyl-4, 4-dimethylheptane.
- 4, 4-Dimethyl-3-ethylheptane.
- 5-Ethyl-4, 4-dimethylheptane.
- 4, 4-Bis (methyl)-3-ethylheptane.
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Ans: 1. 3-Ethyl-4, 4-dimethylheptane.
Explanation:
While writing IUPAC name, the alkyl groups are written in alphabetical order. Thus lower locant 3 is assigned to ethyl. Prefix, di, tri, and tetra are
not included in alphabetical order.
Q25. During hearing of a court case, the judge suspected that some changes in the documents had been carried out. He asked the
forensic department to check the ink used at two different places. According to you which technique can give the best
results?
- Column chromatography.
- Solvent extraction.
- Distillation.
- Thin layer chromatography.
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Ans: 4. Thin layer chromatography.
Explanation:
Thin layer Chomatography (TLC): itis a method for analyzing mixtures by separating the components of the mixture. TLC can be used to determune
the number of components in the mixture, the identity of compounds and the purity of compounds by observing the apperance of a product or
the disppearance of areactant. it can also be used to monitor the progress of a reaction. TLC is a sensitive technique – microgram (0.000001)g
quantities can be analyzwd by TLC,
Q26. In the Kjeldahl’s method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75g of sample
neutralised 10mL of 1M H2SO. The percentage of nitrogen in the soil is:
- 37.33
- 45.33
- 35.33
- 45.33
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Ans: 1. 37.33
Q27. Nucleophile is a species that should have:
- A pair of electrons to donate.
- Positive charge.
- Negative charge.
- Electron deficient species.
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Ans: 1. A pair of electrons to donate.
3. Negative charge.
Q28. In Carius method of estimation of halogens, 250mg of an organic compound gave 141mg of AgBr. The percentage of bromine
in the compound is (atomic mass Ag = 108 and Br = 80)
- 24
- 36
- 48
- 60
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Ans: 1. 24
Q29. What is the technological applications of fractional distillation?
- To separate different fractions of crude oil in petroleum industry.
- To separate different fractions of volatile and non-volatile solvents.
- To separate mixture of amino acids.
- No technological application of fractional distillation.
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Ans: 1. To separate different fractions of crude oil in petroleum industry.
Q30. Glycerol can be separated from spent-lye in soap industry by:
- Chromatography.
- Sublimation.
- Fractional distillation.
- Distillaltion under reduced pressure.
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Ans: 4. Distillaltion under reduced pressure.
Explanation:
Glycerol decomposes at its boiling point is separated from spent-lye by using distillation under reduced pressure.