Q101. An ionic bond is formed by the:
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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Q102. Which of the following compounds exhibits covalent bonding?
Explanation
Covalent bonding occurs when two atoms share one or more pairs of valence electrons to achieve stability. This typically happens between non-metal atoms. In water, each oxygen atom shares electrons with two hydrogen atoms, forming stable covalent bonds. In contrast, substances like sodium chloride and magnesium oxide are held together by ionic bonds resulting from the transfer of electrons between metals and non-metals.
Q103. Metallic bonds are generally characterized by a lattice of positive ions surrounded by a "sea" of:
Explanation
Metallic bonding is characterized by a unique structure where positive metal ions are arranged in a rigid lattice. These ions are surrounded by a "sea" of delocalized valence electrons that are free to move throughout the entire solid. This mobility of electrons is responsible for the characteristic properties of metals, such as high electrical and thermal conductivity, malleability, and metallic luster.
Q104. Consider the following properties of ionic compounds:
I. They generally have high melting and boiling points.
II. They conduct electricity in the solid state.
III. They conduct electricity when dissolved in water.
IV. They are typically soluble in non-polar solvents like benzene.
Which of the above statement(s) is/are correct?
I. They generally have high melting and boiling points.
II. They conduct electricity in the solid state.
III. They conduct electricity when dissolved in water.
IV. They are typically soluble in non-polar solvents like benzene.
Which of the above statement(s) is/are correct?
Explanation
Ionic compounds are characterized by strong electrostatic forces, leading to high melting and boiling points. In their solid state, ions are fixed in a lattice and cannot move, making them poor conductors. However, when dissolved in water or melted, the ions become free to move and conduct electricity. Most ionic compounds are soluble in polar solvents like water but not in non-polar ones.
Q105. Covalent compounds generally have low melting and boiling points because:
Explanation
Covalent compounds consist of individual molecules held together by strong internal covalent bonds. However, the forces acting between these separate molecules, known as intermolecular forces, are relatively weak. When these substances are heated, only a small amount of thermal energy is needed to overcome these weak attractions and separate the molecules, resulting in typically low melting and boiling points compared to ionic compounds.
Q106. The exceptionally high boiling point of water relative to other similar sized molecules is primarily due to:
Explanation
Water molecules are polar, with oxygen being more electronegative than hydrogen. This creates dipoles that lead to a special type of intermolecular attraction called hydrogen bonding. These bonds are much stronger than typical van der Waals forces. Consequently, significant thermal energy is required to break these attractions and transition water from a liquid to a gas, explaining its unusually high boiling point.
Q107. A coordinate covalent (dative) bond is one in which:
Explanation
A coordinate covalent bond, also known as a dative bond, is a specific type of covalent link where the shared pair of electrons is provided entirely by one of the two atoms. The donor atom must have a lone pair of electrons, while the acceptor atom usually has a vacant orbital to accommodate the pair. Once formed, it is indistinguishable from a standard covalent bond.
Q108. Electronegativity is defined as the tendency of an atom to:
Explanation
Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons toward itself within a covalent bond. Atoms with high electronegativity pull electrons more strongly than atoms with lower values. This unequal sharing leads to the formation of polar bonds and influences the overall polarity and reactivity of the resulting molecule in chemical reactions.
Q109. Which of the following molecules has a nonpolar covalent bond?
Explanation
A nonpolar covalent bond occurs when electrons are shared equally between two atoms of the same element, as they have identical electronegativity. In a nitrogen molecule, the two nitrogen atoms share three pairs of electrons equally, resulting in no partial charges. In contrast, molecules like water and ammonia have polar bonds because their different atoms have varying strengths of attraction for the shared electrons.
Q110. Match the substances in List I with their dominant bond type in List II.
| Substance | Dominant Bond Type |
|---|---|
| A. Potassium Chloride (KCl) | i. Metallic bond |
| B. Methane (CH 4 ) | ii. Ionic bond |
| C. Copper wire (Cu) | iii. Coordinate bond (includes) |
| D. Ammonium ion (NH4 + ) | iv. Covalent bond |
Explanation
Potassium chloride is an ionic compound formed by electron transfer. Methane features covalent bonds where electrons are shared between carbon and hydrogen. Copper wire exhibits metallic bonding with a sea of delocalized electrons. The ammonium ion is notable for containing a coordinate covalent bond, where the nitrogen atom donates an electron pair to a hydrogen ion. These examples highlight the major bonding categories.Answer key for these questions
| Q | Correct answer |
|---|---|
| 101 | (c) Complete transfer of one or more electrons from one atom to another |
| 102 | (b) Water (H₂O) |
| 103 | (d) Delocalized valence electrons |
| 104 | (a) I and III only |
| 105 | (c) Intermolecular forces between molecules are relatively weak |
| 106 | (a) Hydrogen bonding |
| 107 | (d) One atom donates both electrons to the shared pair |
| 108 | (b) Attract a shared electron pair in a covalent bond |
| 109 | (c) N₂ |
| 110 | (a) A-ii, B-iv, C-i, D-iii |
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.