Q601. Buckminsterfullerene is an allotropic form of carbon containing how many carbon atoms in its spherical molecule?
RAS Prelims MCQ Practice
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Q602. Hydrocarbons that contain at least one carbon-carbon double or triple bond are classified as:
Explanation
Hydrocarbons are organic compounds composed entirely of hydrogen and carbon. Saturated hydrocarbons, like alkanes, contain only single bonds between carbon atoms. In contrast, unsaturated hydrocarbons possess at least one carbon-carbon double bond, as in alkenes, or a triple bond, as in alkynes. These multiple bonds make unsaturated compounds generally more reactive than their saturated counterparts, as they can undergo chemical addition reactions.
Q603. A series of organic compounds that have the same functional group and similar chemical properties, differing by a -CH 2 unit, is called a:
Explanation
A homologous series is a group of organic compounds that share the same functional group and exhibit similar chemical properties. Each successive member in the series differs from the previous one by a constant methylene unit, which is one carbon and two hydrogen atoms. This structural regularity leads to a predictable gradation in physical properties, such as boiling points, as the molecular mass increases.
Q604. Compounds with the same molecular formula but different structural formulas are known as:
Explanation
Isomers are chemical compounds that have identical molecular formulas but different structural arrangements of their atoms. Because the atoms are linked in different ways or organized differently in space, isomers can exhibit significantly different physical and chemical properties. This phenomenon is particularly prevalent in organic chemistry, where the complexity of carbon chains allows for numerous ways to assemble the same atoms.
Q605. The functional group -COOH is characteristic of which class of organic compounds?
Explanation
The functional group composed of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group is called a carboxyl group. It is represented by the formula dash C O O H. Organic compounds containing this specific group are classified as carboxylic acids. Examples include acetic acid found in vinegar and citric acid found in citrus fruits, which exhibit acidic properties.
Q606. Match the functional groups in List I with the suffixes used in IUPAC naming in List II.
| Functional Group | Suffix used in IUPAC naming |
|---|---|
| A. Alcohol (-OH) | i. -oic acid |
| B. Aldehyde (-CHO) | ii. -one |
| C. Ketone (-CO-) | iii. -al |
| D. Carboxylic acid (-COOH) | iv. -ol |
Explanation
In organic chemistry nomenclature, specific suffixes identify functional groups. Alcohols are designated with the suffix "-ol," while aldehydes end in "-al." Ketones are identified by the suffix "-one," and carboxylic acids use "-oic acid." These standardized IUPAC rules ensure that the name of a compound clearly reflects its chemical structure and the primary functional group responsible for its characteristic reactivity.
Q607. The chemical process of making soap by heating animal fats or vegetable oils with a strong base is called:
Explanation
Saponification is the chemical process used to manufacture soap. It involves the alkaline hydrolysis of esters, typically fats or oils, by heating them with a strong base like sodium hydroxide or potassium hydroxide. This reaction breaks down the triglycerides into glycerol and the salts of fatty acids, which we use as soap. The resulting molecules have both hydrophilic and hydrophobic parts.
Q608. The main constituent of biogas (gobar gas) and natural gas is:
Explanation
Methane is the primary component of both natural gas and biogas, which is produced by the anaerobic decomposition of organic matter like cow dung or agricultural waste. It is a simple hydrocarbon with one carbon atom and four hydrogen atoms. Because it burns cleanly and releases significant energy, methane is a vital fuel source for heating, cooking, and generating electricity worldwide.
Q609. The property of metals by which they can be beaten into thin sheets is known as:
Explanation
Malleability is a physical property of metals that allows them to be hammered, pressed, or rolled into thin sheets without breaking or cracking. This occurs because the layers of atoms in a metallic lattice can slide over each other when pressure is applied. Gold is the most malleable of all metals, followed by silver and aluminum, making them useful for various industrial applications.
Q610. Which of the following metals exists as a liquid at room temperature?
Explanation
Mercury is a unique chemical element that is classified as a metal but remains in a liquid state at standard room temperature and pressure. This behavior is due to its unique electronic configuration, which results in weak bonding between its atoms. Because it is a liquid and a good conductor, it has been widely used in thermometers, barometers, and various electrical switches.Answer key for these questions
| Q | Correct answer |
|---|---|
| 601 | (c) 60 |
| 602 | (b) Unsaturated hydrocarbons |
| 603 | (c) Homologous series |
| 604 | (d) Isomers |
| 605 | (a) Carboxylic acids |
| 606 | (a) A-iv, B-iii, C-ii, D-i |
| 607 | (b) Saponification |
| 608 | (a) Methane |
| 609 | (c) Malleability |
| 610 | (d) Mercury |
Frequently asked questions
How many RAS Prelims practice MCQs are there on RAS Prelims?
This page has 9654 practice MCQs on the RAS Prelims syllabus. Each has the correct answer, and most have an explanation.
How should I practise MCQs for RAS Prelims?
Attempt each question first, then open the answer and read the explanation. Practise one chapter at a time, note the facts you got wrong and revise them. Repeat the chapter after a few days.
Are these actual RAS Prelims past-paper questions?
No. These are practice questions written for the RAS Prelims syllabus. They follow the pattern the exam uses: factual questions, statement-based questions, match-the-list and assertion-reason.