Railway Science (Chemistry-Organic Chemistry) (Part-III)

Total Questions: 15

1. Alkenes, unsaturated hydrocarbon containing a double bond between two carbon atoms, have a general formula, which is: [RRB Group D 31/10/2018 (Afternoon)]

Correct Answer: (a) CₙH₂ₙ
Solution:

Alkenes contain carbon-carbon double bonds and are unsaturated hydrocarbons. Alkanes (CₙH₂ₙ₊₂) are organic compounds that consist of single-bonded carbon and hydrogen atoms. Alkynes ( CₙH₂ₙ₋₂) are hydrocarbons which contain carbon-carbon triple bonds.

2. Hydrocarbons which have the same molecular formula but different structural formula are called _____. [RRB Group D 31/10/2018 (Evening)]

Correct Answer: (b) isomers
Solution:

Isotopes have the same number of protons but different numbers of neutrons, resulting in different masses but not different structures. Isobars are atoms or nuclides of separate chemical elements having the same number of nucleons (protons + neutrons).

3. Select the one that is different from the IUPAC names given below. [RRB Group D 15/11/2018 (Morning)]

Correct Answer: (a) C₃H₅OH → Propanol → Propyl alcohol
Solution:

The International Union of Pure and Applied Chemistry (IUPAC) developed a system for naming chemical compounds to ensure each compound has a unique name. Examples- C₃H₈OH → Propanol → Propyl alcohol.

4. Which allotrope of carbon is in the form of geodesic globe? [RRB Group D 15/11/2018 (Afternoon)]

Correct Answer: (a) Fullerene
Solution:

It is the allotrope of carbon that has a geodesic dome-like structure. It is identified as C-60.

5. Choose the wrong option for aldehyde. [RRB Group D 26/11/2018 (Evening)]

Correct Answer: (b) CH₂COH → ethyl → acetaldehyde
Solution:

Aldehyde- It is an organic compound in which the carbonyl group is attached to a carbon atom at the end of a carbon chain.

6. Glucose is a____carbon molecule. [RRB Group D 1/12/2018 (Afternoon)]

Correct Answer: (a) 6
Solution:

Glucoses molecular formula is C₆H₁₂O₆ , indicating that it contains 6 Carbon atoms, 12 Hydrogen atoms, and 6 Oxygen atoms.

7. Number of σ and π bonds in benzene, respectively, is: [RRB ALP Tier - I (13/08/2018) Morning]

Correct Answer: (b) 12 and 3
Solution:

Sigma bond ( σ ) is a covalent bond which is formed by the head-on overlapping between atomic orbitals. Pi bonds (π) are covalent chemical bonds where two lobes of an orbital on one atom overlap two lobes of an orbital on another atom, and this overlap occurs laterally, Each of these atomic orbitals has zero electron density at a shared nodal plane, passing through the two bonded nuclei.

8. Which of the following is used as a catalyst in the hydrogenation of vegetable oil? [RRB ALP Tier - I (21/08/2018) Evening]

Correct Answer: (d) Ni
Solution:

Hydrogenation - The process of adding hydrogen to an alkene or alkyne in presence of a catalyst to form a saturated hydrocarbon. This process is used to improve the oxidative stability of vegetable oils for improved shelf life and to modify the solid's content and melting characteristics of the oil.
In this process, the unsaturated double bonds in the fatty acids of the oil molecules react with hydrogen atoms in the presence of a catalyst. Another compound or element (as catalyst) - palladium, platinum.

9. Select the INCORRECT set of Molecular Formula- IUPAC Name - Common Name from the following options. [RRB ALP Tier - I (29/08/2018) Evening]

Correct Answer: (b) 𝐶₃ 𝐻₈ OH – Propanol – Propyl Alcohol
Solution:

Isopropyl alcohol (C₃H₈O) commonly referred to as Isopropanol or n-propano. (IUPAC) - International Union of Pure and Applied Chemistry. Some other compounds and their IUPAC Name :- C₄H₉OH - Butyl Alcohol, C₂H₅OH - Ethyl Alcohol, C₂H₃ OH - Vinyl Alcohol.

10. Select the INCORRECT set of Molecular Formula - IUPAC Name - Common Name from the following options. [RRB ALP Tier - I (31/08/2018) Morning]

Correct Answer: (d) C₂H₃OH – Methanol – Methyl Alcohol
Solution:

CH₃OH – Methanol or Methyl Alcohol (also called Wood alcohol). The International Union of Pure and Applied Chemistry (IUPAC) : Established in 1919, Headquarter - Research Triangle Park, North Carolina, United States of America.