Q121. The unique ability of carbon atoms to form long chains or rings by bonding with each other is known as:
Science and Technology: RAS Prelims MCQs
1113 RAS Prelims practice MCQs on science and technology are on this page, in 6 chapters. They cover the basics of everyday science, computers and information technology, defence and space technology in India, genetics, biotechnology and nanotechnology, science and technology policies and government programmes, and recent advances with Indian contributors and indigenisation. Each question has an answer and an explanation.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
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Q122. Given below are two statements: one is labelled as Assertion (A) and the other is labelled as
Reason (R).
Assertion (A): Graphite is a good conductor of electricity, whereas diamond is not.
Reason (R): In graphite, each carbon atom has one free, delocalized electron, whereas in diamond, all four valence electrons are used in covalent bonding.
Reason (R).
Assertion (A): Graphite is a good conductor of electricity, whereas diamond is not.
Reason (R): In graphite, each carbon atom has one free, delocalized electron, whereas in diamond, all four valence electrons are used in covalent bonding.
Explanation
Graphite and diamond are allotropes of carbon with different structures. In diamond, each carbon atom is covalently bonded to four others in a rigid tetrahedron, leaving no free electrons. In graphite, each atom is bonded to only three others in layers, leaving one delocalized electron per atom. These free electrons are mobile, allowing graphite to conduct electricity, whereas diamond remains an insulator.
Q123. Buckminsterfullerene is an allotropic form of carbon containing how many carbon atoms in its spherical molecule?
Explanation
Buckminsterfullerene is a unique allotrope of carbon where sixty carbon atoms are arranged in a hollow, spherical structure resembling a soccer ball. This molecule, often called a "buckyball," consists of interconnected pentagons and hexagons. Discovered in the late twentieth century, it has distinctive physical and chemical properties that have opened new fields in nanotechnology, material science, and potential medical delivery systems.
Q124. 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.
Q125. 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.
Q126. 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.
Q127. 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.
Q128. 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.
Q129. 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.
Q130. 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.Answer key for these questions
| Q | Correct answer |
|---|---|
| 121 | (c) Catenation |
| 122 | (a) Both A and R are true and R is the correct explanation of A. |
| 123 | (c) 60 |
| 124 | (b) Unsaturated hydrocarbons |
| 125 | (c) Homologous series |
| 126 | (d) Isomers |
| 127 | (a) Carboxylic acids |
| 128 | (a) A-iv, B-iii, C-ii, D-i |
| 129 | (b) Saponification |
| 130 | (a) Methane |
Key facts from Science and Technology
- The RPSC paper is General Knowledge and General Science, so science questions come with a strong dose of applied and recent topics.
- Everyday science questions test the laws and terms of physics, chemistry and biology through examples.
- Defence and space questions pair a missile, satellite or mission with its year and organisation.
- Policy questions ask for the year, the body and the aim of schemes like STIP, the National Quantum Mission and BioE3.
- Health, environment and agriculture are on a separate page, with their own chapters.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Science and Technology?
This page has 1113 practice MCQs on Science and Technology. Each has the correct answer, and most have an explanation.
Which chapters does the science and technology set cover?
Six chapters: basics of everyday science; computers, information and communication technology; defence and space technology in India; genetics, biotechnology and nanotechnology; science and technology policies and government programmes; and recent advances, Indian contributors and indigenisation.
Is science and technology part of the RAS Prelims syllabus?
Yes. The RPSC paper is called General Knowledge and General Science, and its syllabus lists science and technology topics along with environment, health, agriculture and government programmes, so questions can come from any of these areas.
How should I prepare science for RAS Prelims?
Revise the concepts by examples, then learn the missions, schemes and scientists with their year and organisation. Attempt each chapter, read the explanations and keep a list of the facts you missed.