Purification and Organic Compounds Quiz | Chemistry Quiz
The word ‘organic’ signifies life. Therefore, all substances which were obtained directly or indirectly from living organisms, plants and animals were called organic compounds and the branch of chemistry which deals with these compounds was called organic chemistry.
The modern definition of organic chemistry: Organic chemistry is the chemistry of hydrocarbons and their derivatives in which covalently bonded carbon is an essential constituent.
Berzelius put forward a theory in 1815 known as vital force theory. According to this theory, "organic compounds could be prepared only by living organisms under the influence of a mysterious force known as a vital force". Accidental synthesis of urea by Wohler and synthesis of acetic acid by Kolbe led to the fall of this theory.
Berthelot prepared methane in the laboratory and the most abundant organic compound is cellulose which is a polymer of glucose. Kekule and Couper proposed the tetravalency of carbon and wrote the first structural formula. In 1874, Van't Hoff and Le Bell suggested a tetrahedron model of carbon.
Purification and Characterisation of organic
compounds
The study of organic compounds starts with the characterization of the compound and the determination of its molecular structure. The procedure generally employed for this purpose consists of the following steps :
(1) Purification of organic compounds
(2) Qualitative analysis of organic compounds
(3) Quantitative analysis of organic compounds
(4) Determination of the molecular mass of organic compounds
(5) Calculation of Empirical formula and Molecular formula of organic compounds
(6) Determination of the structure of organic compounds by spectroscopic and diffraction methods
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Chemical Analysis of Organic Compounds Quiz
1. Which of the following is the best scientific method to test the presence of water in a liquid
(a) Use of anhydrous copper sulphate
(b) Use of litmus paper
(c) Taste
(d) Smell
Sol: (a) Anhydrous CuSO4 is used to test presence of water in any liquid because it changes its colour white to blue.
2. Chromatography is a valuable method for the separation, isolation, purification and identification of the constituents of a mixture and it is based on general principle of
(a) Phase rule
(b) Phase distribution
(c) Interphase separation
(d) Phase operation
Sol: A
3. If we want to study relative arrangement of atoms in a molecule we study
(a) Empirical formula
(b) Molecular formula
(c) Structural formula
(d) None of these
Sol: C
4. The decomposition of organic compounds in the presence of oxygen and without formation of odoriferous substances, is called
(a) Decay (b) N2 fixation
(c) Nitrification (d) Denitrification
Sol: A
5. Quantitative measurement of nitrogen in an organic compounds is done by the method
(a) Berthelot method
(b) Belstein method
(c) Lassaigne test
(d) Kjheldahl's method
Sol: (d) Kjeldahl's and Duma’s methods are used for the quantitative estimation of nitrogen in an organic compound. In the Kjeldahl method, the nitrogen element of organic compound is changed to the ammonia.
6. Which kind of fission is favoured by sunlight
(a) Heterolytic fission
(b) Homolytic fission
(c) Both (a) and (b)
(d) None of these
Sol: (b) Homolytic fission is favoured by sunlight. In it, each bonded atom takes away its shared electrons and thus free radicals are produced.
7. The ammonia evolved from the treatment of 0.30 g of an organic compound for the estimation of nitrogen was passed in 100 mL of 0.1 M sulphuric acid. The excess of acid required 20 mL of 0.5 M sodium hydroxide solution for complete neutralization. The organic compound is
(a) Urea (b) Benzamide
(c) Acetamide (d) Thiourea
Sol: (a)
8. The IUPAC name of CH3COOC2H5 will be
(a) Ethyl acetate
(b) Ethyl ethanoate
(c) Methyl propanoate
(d) None of these
Sol B
9. IUPAC name of (CH3)2CH-CHO is:
(a) 2-methyl propanal
(b) 1-methyl-2 propanal
(c) 2, 2-dimethyl propanal
(d) None of these
Sol: A
Purification and Organic Compounds Quiz | Chemistry Quiz
10. The compound which has one isopropyl group is
(a) 2, 2, 3, 3-tetramethyl pentane
(b) 3, 3-dimethyl pentane
(c) 2, 2, 3-trimethyl pentane
(d) 2-methyl pentane
Sol: D
11. If CH4 is known as methane, then C9H20 is known as
(a) Hexane (b) Nonane
(c) Octane (d) Butane
Sol: B
12. The IUPAC name of n-butyl chloride is
(a) 1-chlorobutane
(b) n-chlorobutane
(c) ter-butylchloride
(d) 2-methylbutane
Sol: A
13. Which of the following compounds is not chiral
(a) 1-chloro-2-methyl pentane
(b) 2-chloropentane
(c) 1-chloropentane
(d) 3-chloro-2-methyl pentane
Sol: (a) To be optically active the compound or structure should possess chiral or a symmetric centre but in the rest of the structures it is present.
14. Camphor is often used in molecular mass determination because
(a) It is volatile
(b) It is solvent for organic substances
(c) It is readily available
(d) It has a very high cryoscopic constant
Sol: (a) Due to its volatile nature camphor is often used in molecular mass determination.
15. In Kjeldahl’s method, the nitrogen present in the organic compound is quantitatively converted into
(a) Gaseous ammonia
(b) Ammonium sulphate
(c) Ammonium phosphate
(d) Ammonia
Sol: (d) In Kjeldahl’s method, the nitrogen is estimated in the form of ammonia, which is obtained by heating compounds with .