Q91. The nucleus of an atom consists of which of the following subatomic particles?
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.
Showing 91–100 of 1113 questions
Browse Science and Technology chapters
Q92. Consider the following statements regarding the electron:
I. It has a negative electrical charge.
II. Its mass is approximately 1/1836 that of a proton.
III. It resides strictly within the nucleus of an atom.
Which of the above statement(s) is/are correct?
I. It has a negative electrical charge.
II. Its mass is approximately 1/1836 that of a proton.
III. It resides strictly within the nucleus of an atom.
Which of the above statement(s) is/are correct?
Explanation
Electrons are fundamental subatomic particles with a negative charge. Their mass is extremely small, approximately one eighteen-hundred-thirty-sixth that of a proton. Crucially, electrons do not reside within the nucleus; instead, they are found in the space surrounding the nucleus, organized into energy levels. This external positioning is essential for chemical bonding and electrical conductivity in materials.
Q93. The atomic number of an element represents the total number of:
Explanation
The atomic number is a fundamental property of an element that defines its identity. It represents the total number of protons found in the nucleus of every atom belonging to that element. In a neutral atom, the atomic number also equals the number of electrons. Because the number of protons determines the chemical behavior, no two different elements share the same atomic number.
Q94. Atoms of the same element that have the same atomic number but different mass numbers are called:
Explanation
Isotopes are variants of a particular chemical element that have the same number of protons and thus the same atomic number. However, they differ in the number of neutrons in their nuclei, resulting in different mass numbers. While isotopes of an element share almost identical chemical properties, they may exhibit different physical properties and varying levels of stability or radioactive decay.
Q95. Isobars are atoms of different elements that possess:
Explanation
Isobars are atoms of different chemical elements that possess the same mass number but have different atomic numbers. This means they have the same total number of nucleons (protons plus neutrons) in their nuclei, but the specific ratio of protons to neutrons varies. Because they have different atomic numbers, isobars belong to different elements and exhibit distinct chemical and physical properties.
Q96. Which scientist proposed the planetary model of the atom, where electrons revolve in discrete circular orbits around the nucleus?
Explanation
Niels Bohr proposed a revolutionary atomic model in 1913, often described as the planetary model. He suggested that electrons revolve around the nucleus in specific, discrete circular orbits with fixed energy levels. In this model, electrons can only exist in these allowed orbits and can jump between them by absorbing or emitting energy, explaining the unique spectral lines observed in hydrogen atoms.
Q97. Ernest Rutherford’s gold foil experiment led to the discovery of the:
Explanation
Ernest Rutherford’s famous gold foil experiment involved firing alpha particles at a thin sheet of gold. While most particles passed through, some were deflected at large angles. This unexpected result led to the conclusion that atoms are mostly empty space, with their positive charge and most of their mass concentrated in a tiny, dense central region which Rutherford named the atomic nucleus.
Q98. Arrange the following atomic models in chronological order of their proposal:
I. Bohr’s model
II. Dalton’s solid sphere model
III. Thomson’s plum pudding model
IV. Rutherford’s nuclear model
Which of the following is the correct order?
I. Bohr’s model
II. Dalton’s solid sphere model
III. Thomson’s plum pudding model
IV. Rutherford’s nuclear model
Which of the following is the correct order?
Explanation
The understanding of atomic structure evolved through several key models. John Dalton first proposed the solid sphere model in the early eighteen-hundreds. J.J. Thomson followed with the "plum pudding" model after discovering the electron. Ernest Rutherford then introduced the nuclear model based on his scattering experiments. Finally, Niels Bohr refined this by adding quantized electron orbits, creating the modern planetary model.
Q99. The combining capacity of an element with other elements is fundamentally determined by its:
Explanation
Valency is the measure of an element’s combining capacity with other atoms when forming chemical compounds or molecules. It is fundamentally determined by the number of electrons in the atom’s outermost shell, known as valence electrons. Atoms tend to gain, lose, or share these electrons to achieve a stable electronic configuration, typically resembling that of the nearest noble gas in the periodic table.
Q100. In the modern periodic table, elements are arranged in increasing order of their:
Explanation
The modern periodic table organizes chemical elements based on their increasing atomic number, which is the number of protons in an atom’s nucleus. This arrangement, established by Henry Moseley, replaced earlier versions based on atomic mass. By using atomic numbers, elements with similar electronic configurations and chemical properties fall into the same vertical columns, known as groups, revealing clear periodic trends.Answer key for these questions
| Q | Correct answer |
|---|---|
| 91 | (d) Protons and neutrons |
| 92 | (a) I and II only |
| 93 | (c) Protons in its nucleus |
| 94 | (d) Isotopes |
| 95 | (a) The same mass number but different atomic numbers |
| 96 | (b) Niels Bohr |
| 97 | (b) Atomic nucleus |
| 98 | (a) II, III, IV, I |
| 99 | (c) Valency |
| 100 | (d) Atomic number |
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.