Hydrocarbons (Alkane, Alkene and Alkyne) MCQ Questions & Answers in Organic Chemistry | Chemistry

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The reaction follows Markownikoff rule which states that when unsymmetrical reagent adds across unsymmetrical double or triple bond the negative part adds to carbon atom having lesser number of hydrogen atoms.

\[Ca{{C}_{2}}\xrightarrow{{{H}_{2}}O}\underset{\begin{smallmatrix} \text{Acetylen e} \\ \left( A \right) \end{smallmatrix}}{\mathop{HC\equiv CH}}\,\]     \[\xrightarrow[H{{g}^{+2}}]{Dil.\,{{H}_{2}}S{{O}_{4}}}\underset{\begin{smallmatrix} \text{Acetaldehyde} \\ \left( B \right) \end{smallmatrix}}{\mathop{C{{H}_{3}}CHO}}\,\xrightarrow[{{H}_{2}}]{Ni}\]       \[\underset{\left( C \right)}{\mathop{{{C}_{2}}{{H}_{5}}OH}}\,\]

$$FeC{l_3}$$  is Lewis acid. In presence of $$FeC{l_3}$$  side chain hydrogen atoms of toluene are substituted.

TIPS/Formulae :
Addition on triple bond takes place by the syn-addition of hydrogen.
Since the configuration of the double bond already present is cis, the compound formed will have a plane of symmetry and hence optically inactive.

\[{{C}_{5}}{{H}_{12}}:\underset{n\text{-Pentane}}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}C{{H}_{3}}}}\,\]
\[\underset{\text{2-Methylbutane (iso-Pentane)}}{\mathop{C{{H}_{3}}\underset{\begin{smallmatrix} |\,\,\,\,\, \\ C{{H}_{3}} \end{smallmatrix}}{\mathop{-CH-}}\,C{{H}_{2}}-C{{H}_{3}}}}\,,\]       \[\underset{\begin{smallmatrix} \text{2,2-Dimetbylpropane} \\ \text{(neo-Pentane)} \end{smallmatrix}}{\mathop{C{{H}_{3}}\underset{\begin{smallmatrix} | \\ \,\,\,\,C{{H}_{3}} \end{smallmatrix}}{\overset{\begin{smallmatrix} \,\,\,\,\,C{{H}_{3}} \\ | \end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{3}}}}\,\]

Marsh gas is a gaseous decomposition of organic matter, it consists of methane, hydrogen sulphide and carbon dioxide produces mainly within some geographical marshes, swamps and bogs. It consists primarily of methane. Marsh gas is produces by the anaerobic bacterial decomposition of vegetable matter and the rumen of herbivorous animals. It has the ability to self ignite, which is present in marshes and is visible mainly at night. The marsh gas has 50 to 80 percent methane gas.

The given molecular formula suggests that the aldehyde formed will be acetaldehyde hence the alkene will be

TIPS/Formulae :
Peroxide effect is effective only in case of $$HBr$$  and not in case of $$HCl$$  and $$HI.$$

For $$HCl,$$  Step-I (b) is endothermic while step-II is exothermic but for $$HI,$$  Step-I (b) is exothermic while Step-II is endothermic.