Practice free Hydrocarbons (Chemistry) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
What is the typical energy barrier range (in kJ mol$^{-1}$) that hinders the completely free rotation around a C-C single bond in alkanes?
The NCERT text mentions: 'It is hindered by a small energy barrier of 1-20 kJ mol–1 due to weak repulsive interaction between the adjacent bonds.' (Chapter: Hydrocarbons, Page 305)
Which of the following is NOT an alternative term for conformations?
The context defines conformations as 'spatial arrangements of atoms which can be converted into one another by rotation around a C-C single bond are called conformations or conformers or rotamers.' Tautomers are a different type of isomerism involving proton transfer and rearrangement of electrons. (Chapter: Hydrocarbons, Page 305)
How is the front carbon atom represented in a Newman projection?
According to the NCERT description of Newman projections: 'The carbon atom nearer to the eye is represented by a point.' (Chapter: Hydrocarbons, Page 305)
In a Sawhorse projection, the central C-C bond is depicted as:
The NCERT states for Sawhorse projections: 'It is then projected on paper by drawing the central C–C bond as a somewhat longer straight line.' (Chapter: Hydrocarbons, Page 305)
Why is the staggered conformation of ethane generally more stable than its eclipsed conformation?
The summary states: 'Out of staggered and the eclipsed conformations of ethane, staggered conformation is more stable as hydrogen atoms are farthest apart.' This minimizes torsional strain or repulsive interactions between electron clouds of C-H bonds. (Chapter: Hydrocarbons, Page 326)
Which projection method shows the rear carbon atom as a circle?
The NCERT text on Newman projections states: 'The rear carbon atom (the carbon atom away from the eye) is represented by a circle...' (Chapter: Hydrocarbons, Page 305)
If you keep one carbon atom stationary and rotate the other carbon atom around the C-C axis in ethane, what phenomenon is observed regarding the spatial arrangements of hydrogen atoms?
The NCERT states: 'This rotation results into infinite number of spatial arrangements of hydrogen atoms attached to one carbon atom with respect to the hydrogen atoms attached to the other carbon atom. These are called conformational isomers (conformers). Thus there are infinite number of conformations of ethane.' (Chapter: Hydrocarbons, Page 305)
Which amongst the following molecules on polymerization produces neoprene?
Neoprene = poly(chloroprene); chloroprene is 2-chloro-1,3-butadiene.
Weight (g) of two moles of the organic compound, which is obtained by heating sodium ethanoate with sodium hydroxide in presence of calcium oxide is:
Decarboxylation: CH₃COONa + NaOH (CaO, Δ) → CH₄ + Na₂CO₃. 2 mol CH₄ = 32 g.
Consider the following compounds/species:
i.
ii.
iii.
iv.
v.
vi.
vii.
The number of compounds/species which obey Huckel's rule is:
Aromatic (4n+2): naphthalene (10π), cyclopentadienyl anion (6π), cyclopropenyl cation (2π), anthracene (14π) → 4. Cyclobutadiene & cyclopropenyl anion are antiaromatic; cyclooctatetraene is non-planar.
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