Q1021. The Saha ionization equation, formulated by Meghnad Saha, is fundamentally applied in astrophysics to determine which of the following?
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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Q1022. What is the core concept of thermal ionization as described by Meghnad Saha?
Explanation
Thermal ionization is the process where atoms in a gas become ionized due to high-energy thermal collisions. Meghnad Saha’s theory explains that as temperature increases, atoms move faster and collide more violently. These collisions eventually overcome the binding energy of the electrons, causing them to be ejected. This concept is vital for understanding the plasma state found in stellar atmospheres.
Q1023. Apart from his contributions to astrophysics, Meghnad Saha played a critical role in civil administration by chairing which important committee in 1952?
Explanation
Beyond his scientific achievements, Meghnad Saha was deeply involved in national planning and civil reform. In 1952, he chaired the Indian Calendar Reform Committee, which sought to standardize the various traditional calendars used across the country. His efforts led to the adoption of the Indian National Calendar, based on scientific astronomical principles, which is still used by the government.
Q1024. Identify the correct pair representing Meghnad Saha’s scientific legacy.
Explanation
Meghnad Saha’s most enduring legacy is the Saha equation, which provides the mathematical link between a gas’s temperature, pressure, and its degree of ionization. This equation transformed astrophysics from a descriptive science into a quantitative physical discipline. While other scientists worked on white dwarfs and fermions, Saha’s specific focus on ionization remains the cornerstone for analyzing the spectra of celestial bodies.
Q1025. Arrange the following steps in the logical application of the Saha ionization equation to classify stars:
A. Observation of absorption lines in a star’s spectrum
B. Calculation of the star’s surface temperature
C. Determination of the ionization states of elements present
D. Measurement of the intensity of specific spectral lines
A. Observation of absorption lines in a star’s spectrum
B. Calculation of the star’s surface temperature
C. Determination of the ionization states of elements present
D. Measurement of the intensity of specific spectral lines
Explanation
To classify a star using Saha’s theory, astronomers first observe the absorption lines in the stellar spectrum. They then measure the intensity of these specific lines to gauge the abundance of different elements. By applying the Saha equation, they determine the ionization states of those elements, which finally allows for an accurate calculation of the star’s actual surface temperature.
Q1026. Which of the following statements regarding Meghnad Saha’s institutional foundations is incorrect?
Explanation
Meghnad Saha was a key figure in building India’s scientific infrastructure, founding the Saha Institute of Nuclear Physics and the journal ‘Science and Culture’. He also helped establish the National Academy of Sciences. However, he was not the architect of the Indian Institute of Science in Bangalore; that institution was founded earlier through the vision of Jamsetji Tata and Swami Vivekananda.
Q1027. Consider the following statements:
Statement I: According to the Saha ionization equation, an increase in temperature increases the degree of ionization of a gas.
Statement II: An increase in the electron pressure in the stellar atmosphere also increases the degree of ionization.
Which of the following is correct?
Statement I: According to the Saha ionization equation, an increase in temperature increases the degree of ionization of a gas.
Statement II: An increase in the electron pressure in the stellar atmosphere also increases the degree of ionization.
Which of the following is correct?
Explanation
According to the Saha equation, increasing the temperature of a gas provides more energy for ionization, thereby increasing the degree of ionization. However, an increase in electron pressure actually drives the reaction in the opposite direction, promoting the recombination of ions and electrons into neutral atoms. Therefore, higher electron pressure leads to a lower degree of ionization in a stellar atmosphere.
Q1028. Identify the odd one out among astrophysical concepts that are unrelated to the direct application of the Saha equation.
Explanation
The Saha equation is primarily used to understand the physical conditions of stellar surfaces. It is essential for spectral classification, determining photospheric temperatures, and analyzing the composition of the solar chromosphere. The Hubble constant, however, relates to the rate of expansion of the universe and large-scale cosmic distances, which is a field of cosmology independent of stellar ionization physics.
Q1029. What was the primary effect of Meghnad Saha’s interpretation of solar spectrum lines on the field of astrophysics?
Explanation
Before Saha’s work, stellar spectroscopy was largely a tool for cataloging stars without understanding the underlying physics. His interpretation of spectral lines allowed scientists to calculate the actual temperature and pressure of stellar gases. This shift enabled astronomers to build physical models of stars, marking the birth of modern astrophysics where observations are linked to fundamental thermodynamic and atomic principles.
Q1030. Read the following statements and select the correct option:
Assertion (A): The Saha ionization equation allows astronomers to determine the surface temperature of stars accurately.
Reason (R): The equation quantitatively relates the observed ionization states of elements in stellar spectra to the temperature and pressure of the gas.
Assertion (A): The Saha ionization equation allows astronomers to determine the surface temperature of stars accurately.
Reason (R): The equation quantitatively relates the observed ionization states of elements in stellar spectra to the temperature and pressure of the gas.
Explanation
The Saha ionization equation provides a robust mathematical framework that relates the observable characteristics of a star’s light to its physical state. By analyzing which atoms are ionized and to what degree, astronomers can accurately deduce the surface temperature. The reason correctly identifies that the quantitative relationship between ionization, temperature, and pressure is what makes this determination scientifically possible.Answer key for these questions
| Q | Correct answer |
|---|---|
| 1021 | (d) The physical and chemical state of stellar atmospheres. |
| 1022 | (a) At extremely high temperatures, collisions between atoms are energetic enough to strip electrons from them, creating ions and free electrons |
| 1023 | (c) The Indian Calendar Reform Committee |
| 1024 | (a) Saha equation - Links the ionization state of an element to temperature and pressure |
| 1025 | (a) A, D, C, B |
| 1026 | (b) He was the chief architect of the Indian Institute of Science (IISc), Bangalore |
| 1027 | (c) Statement I is correct but Statement II is incorrect |
| 1028 | (d) Calculation of the expanding universe’s Hubble constant |
| 1029 | (a) It shifted astrophysics from merely observing stellar spectra to understanding the physical conditions producing them |
| 1030 | (a) Both A and R are true and R is the correct explanation of A. |
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.