0

Organic Chemistry

Description: This test contains 25 multiple choice questions on certain topics from organic chemistry.
Number of Questions: 25
Created by:
Tags: steriochemestry reagents alkanes cycloalkanes etc. Alkanes and Cycloalkanes Types of Reagents
Attempted 0/25 Correct 0 Score 0

Alkenes and cycloalkanes exihibit ------------------------ isomerism.

  1. chain

  2. position

  3. functional

  4. geometrical


Correct Option: C
Explanation:

Alkenes and cycloalkanes have the same molecular formula (CnH2n). Since cycloalkanes do not behave as unsaturated hydrocarbons, alkenes and cycloalkanes are termed functional isomers. For instance, propene is isomeric with cyclopropane (or trimethylene).

The heterocyclic compound used in the studies of nucleic acids and proteins is

  1. oxaziridine

  2. oxirene

  3. dioxirane

  4. diazirines


Correct Option: D
Explanation:

Diazirines are a class of organic molecules consisting of a carbon bound to two nitrogen atoms, which are double-bonded to each other, forming a cyclopropene-like ring. They are mainly used as carbene precursor and also in photoaffinity labelling studies of nucleic acids and proteins.

Which of the following alkanes is a component of a pheromone of Orgyia leucostigma?

  1. Hentriacontane

  2. Nonacosane

  3. Tetracosane

  4. Icosane


Correct Option: B
Explanation:

Nonacosane is a straight-chain hydrocarbon. It has 1,590,507,121 constitutional isomers. Nonacosane has been reported to be a component of a pheromone of Orgyia leucostigma, and evidence suggest it plays a role in the chemical communication of several insects, including the female Anopheles stephensi mosquito.

Which of the following exists as small alkaline deliquescent crystals?

  1. Tetrazine

  2. Trioxane

  3. Triazine

  4. Piperazine


Correct Option: D
Explanation:

Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste.

Among the following ----------------------- is most compact and branched isomer of hexane.

  1. 2-Methylpentane

  2. 3-Methylpentane

  3. 2,3-Dimethylbutane

  4. 2,2-Dimethylbutane


Correct Option: D
Explanation:

2,2-Dimethylbutane, trivially known as neohexane, is an organic compound with formula C6H14 or (H3C-)3-C-CH2-CH3. It is therefore an alkane, indeed the most compact and branched of the hexane isomers — the only one with a quaternary carbon and a butane (C4) backbone.

Which of the following is regarded as a standard measure of the anti-knock properties of the fuel?

  1. Cetane number

  2. Cetane index

  3. Isocetane

  4. Octane number


Correct Option: D
Explanation:

Octane rating or octane number is a standard measure of the anti-knock properties (i.e. the performance) of a motor or aviation fuel. The higher the octane number, the lesser likely is the fuel to ignite prematurely in the engine's cycle and cause the engine damage. In broad terms, fuels with a higher octane rating are more suitable for high-performance engines.

Which of the following is the smallest sulphur-containing heterocycle?

  1. Aziridines

  2. Ethylene oxide

  3. Thiirane

  4. Azirines


Correct Option: C
Explanation:

Thiirane, more commonly known as ethylene sulphide, is the cyclic chemical compound with the formula C2H4S. It is the smallest suphur-containing heterocycle. Like many organosulphur compounds, this species has a stench. Thiirane is also used to describe any derivative of the parent ethylene sulphide.

Among the following compounds ----------------------- contains three carbon atoms and one sulphur atom.

  1. oxetane

  2. thietane

  3. dioxetane

  4. dithietane


Correct Option: B
Explanation:

Thietane is a heterocyclic compound containing a saturated four-membered ring with three carbon atoms and one sulphur atom.

Among the following compounds ---------------------- is generally encountered as as anellated derivatives

  1. azete

  2. oxetene

  3. thiete

  4. dithietes


Correct Option: C
Explanation:

Thiete is a heterocycle. It is more commonly encountered not on its own, but in anellated derivatives, several of which have been synthesized. Thietes are generally not very stable.

Among the following aromatic hydrocarbons which one is a known human carcinogen?

  1. Naphthalene

  2. Anthracene

  3. Phenanthrene

  4. Benzo[a]pyrene


Correct Option: D
Explanation:

It has five rings. It also has the faint aromatic odour. Pure benzo[a]pyrene is pale yellow, and is found as monoclinic or orthorhombic crystals. These can be separated from a mixture of polynuclear aromatic hydrocarbons using various standard separation techniques and recrystallized from benzene and methanol. It is known as human carcinogen.

Among the following alkanes which one is used as a working medium in geothermal power stations?

  1. Octane

  2. Hexane

  3. Heptane

  4. Pentane


Correct Option: D
Explanation:

Pentane is an organic compound, with five carbon atoms. Pentane is one of the primary blowing agents used in the production of polystyrene foam. Because of its low boiling point, low cost and relative safety, pentane is used as a working medium in geothermal power stations. It is added into some refrigerant blends as well.

Which of the following alkanes is used as an anti-knock additive in aviation fuels?

  1. Isopentane

  2. Triptane

  3. Tetramethylbutane

  4. 2-Methylpentane


Correct Option: B
Explanation:

Triptane, or 2,2,3-trimethylbutane, is an organic chemical compound with the molecular formula C7H16. It is therefore an alkane, specifically the most compact and heavily branched of the heptane isomers, the only one with a butane (C4) backbone. Triptane is commonly used as an anti-knock additive in aviation fuels.

Which of the following alkanes is a member of the marsh-gas series?

  1. Tridecanes

  2. Hexadecane

  3. Pentadecane

  4. Tetradecane


Correct Option: D
Explanation:

It is a light oily hydrocarbon, of the marsh-gas series. It contains fourteen carbon atoms in the molecule.

Among the following alkanes -------------------- is used as an internal standard in gas chromatography.

  1. dodecane

  2. undecane

  3. decane

  4. nonane


Correct Option: B
Explanation:

Undecane (also known as hendecane) is a liquid alkane hydrocarbon. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants. It has 159 isomers. Undecane may also be used as an internal standard in gas chromatography when working with other hydrocarbons.

Which of the following is the final type of octane rating?

  1. Motor Octane Number (MON)

  2. Research Octane Number (RON)

  3. Anti-Knock Index (AKI)

  4. Observed Road Octane Number (RdON)


Correct Option: D
Explanation:

The final type of octane rating, called Observed Road Octane Number (RdON), is derived from testing gasolines in real world multi-cylinder engines, normally at wide open throttle. It was developed in the 1920's and is still reliable today. The original testing was done in cars on the road but as technology developed, the testing was moved to chassis dynamometers with environmental controls to improve consistency.

The reagent used as an oxidizer in liquid rocket propellants is

  1. antimony trifluoride

  2. arsenic trifluoride

  3. bromine pentafluoride

  4. bromine trifluoride


Correct Option: C
Explanation:

Bromine pentafluoride is an interhalogen compound and a fluoride of bromine. It is a strong fluorination reagent. It is also used as an oxidizer in liquid rocket propellants and as a fluorinating agent in the processing of uranium.

Among the following reagents -------------------- is used as a precursor for fibre-reactive dyes.

  1. iodine pentafluoride

  2. gold(III) fluoride

  3. diethylaminosulfur trifluoride

  4. cyanuric fluoride


Correct Option: D
Explanation:

Cyanuric fluoride or 2,4,6-trifluoro-1,3,5-triazine is a colourless, pungent liquid. It has been used as a precursor for fibre-reactive dyes, as a specific reagent for tyrosine residues in enzymes, and as a fluorinating agent.

Among the following compounds -------------------- releases HF upon exposure to water.

  1. sulphur tetrafluoride

  2. xenon difluoride

  3. xenon hexafluoride

  4. nickel(II) fluoride


Correct Option: A
Explanation:

Sulphur tetrafluoride is the chemical compound. This species exists as a gas at standard conditions. It is a corrosive species that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, some of which are important in the pharmaceutical and chemical industries.

Which of the following reagents is used for the olefination of ketones and aldehydes?

  1. The Nysted reagent

  2. The Tebbe reagent

  3. An Olah reagent

  4. An Organolithium reagent


Correct Option: A
Explanation:

The Nysted reagent is used for the olefination of ketones and aldehydes.

Which of the following reagents converts primary and secondary alcohols to ketones?

  1. Eschenmoser's salt

  2. Reinecke's salt

  3. Frémy's salt

  4. Cornforth salt


Correct Option: D
Explanation:

The Cornforth salt or pyridinium dichromate (PDC) is a pyridinium salt of dichromate. It is a strong oxidizing agent which can convert primary and secondary alcohols to ketones. In its chemical structure and functions, it is closely related to other compounds made from hexavalent chromium oxide, such as pyridinium chlorochromate and Collins reagent.

Among the following reagents which one is used as a means of purifying elemental fluorine?

  1. Manganese(III) fluoride

  2. Manganese tetrafluoride

  3. Nitrosyl fluoride

  4. Nitryl fluoride


Correct Option: B
Explanation:

Manganese tetrafluoride is the highest fluoride of manganese. It is a powerful oxidizing agent and is used as a means of purifying elemental fluorine.

Which of the following reagents is used in industrial cleaning and etching operations in the semiconductor industry?

  1. Chlorine monofluoride

  2. Chlorine pentafluoride

  3. Chlorine trifluoride

  4. Cobalt(III) fluoride


Correct Option: C
Explanation:

Chlorine trifluoride is an interhalogen compound. This colourless, poisonous, corrosive and very reactive gas condenses to a pale-greenish yellow liquid. The compound is primarily of interest as a component in rocket fuels, in industrial cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing and other industrial operations.

Among the following ---------------------- is paramagnetic in nature.

  1. perchloryl fluoride

  2. platinum hexafluoride

  3. selenium tetrafluoride

  4. silver(II) fluoride


Correct Option: B
Explanation:

Platinum hexafluoride is the chemical compound. It is a dark-red volatile solid that forms a red gas. The compound is a unique example of platinum in the +6 oxidation state. With only four d-electrons, it is paramagnetic with a triplet ground state.

Which of the following is commercially available as solutions of hexanes, heptane or toluene?

  1. Diethylzinc

  2. Diisopinocampheylborane

  3. Dimethyldioxirane (DMDO)

  4. Diphenylphosphoryl azide


Correct Option: A
Explanation:

Diethylzinc is an organozinc compound composed of zinc bonded to two ethyl groups. This colourless liquid is an important reagent in organic chemistry and available commercially as solutions of hexanes, heptane or toluene.

Among the following -------------------serves as a precursor to food and fertilizers.

  1. acetic acid

  2. acetone

  3. acetylene

  4. ammonia


Correct Option: D
Explanation:

Ammonia is a compound of nitrogen and hydrogen . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers.

- Hide questions