Q181. Why are synthetic detergents generally preferred over traditional soaps for washing clothes in hard water?
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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Q182. Consider the following statements about bleaching powder (Calcium oxychloride):
I. It is produced by the action of chlorine gas on dry slaked lime.
II. It is used for disinfecting drinking water.
III. It releases oxygen gas when left open in the air.
Which of the above statement(s) is/are correct?
I. It is produced by the action of chlorine gas on dry slaked lime.
II. It is used for disinfecting drinking water.
III. It releases oxygen gas when left open in the air.
Which of the above statement(s) is/are correct?
Explanation
Bleaching powder is produced by reacting chlorine gas with dry slaked lime, a process that yields calcium oxychloride. It is highly effective as a disinfectant for treating drinking water and as a bleaching agent in textiles. However, it does not release oxygen when exposed to air; instead, it reacts with atmospheric carbon dioxide to slowly release chlorine gas, providing its pungent odor.
Q183. Which of the following chemicals is commonly used as a commercial food preservative for fruit juices and jams?
Explanation
Sodium benzoate is a widely used food preservative, particularly in acidic products like fruit juices, carbonated drinks, jams, and pickles. It works by inhibiting the growth of potentially harmful bacteria, yeasts, and molds. By maintaining a low pH environment, it effectively extends the shelf life of processed foods while preserving their flavor and safety, making it a staple in food production.
Q184. Saccharin and aspartame are primarily used in the food industry as:
Explanation
Saccharin and aspartame are popular artificial sweetening agents used as low-calorie alternatives to sucrose, or common table sugar. They are many times sweeter than natural sugar, meaning only tiny amounts are required to achieve the desired level of sweetness. These compounds are particularly useful for individuals with diabetes or those looking to reduce their caloric intake without sacrificing sweet taste in foods.
Q185. Monosodium glutamate (MSG) is added to packaged foods primarily to:
Explanation
Monosodium glutamate, commonly referred to as MSG, is a sodium salt derived from the amino acid glutamic acid. It is added to various packaged and processed foods primarily to enhance their savory, meaty flavor, often described as "umami." While it occurs naturally in some foods like tomatoes and cheeses, its concentrated form is used by the food industry to intensify the taste.
Q186. Chemicals applied to living tissues to kill or prevent the growth of microbes are called:
Explanation
Antiseptics are chemical substances specifically designed to be applied to living tissues, such as skin or wounds, to kill or inhibit the growth of microorganisms. Unlike disinfectants, which are stronger and used on inanimate objects like floors, antiseptics must be safe enough to prevent infection without causing significant damage to the host’s cells. Common examples include iodine and alcohol solutions.
Q187. Toothpastes are generally formulated to be slightly basic in nature. What is the primary chemical reason for this?
Explanation
Bacteria in the mouth ferment food particles, particularly sugars, to produce organic acids that can erode tooth enamel and lead to cavities. Toothpastes are formulated to be slightly basic to effectively neutralize these harmful acids. This neutralizing action helps to maintain a healthy pH balance in the oral cavity, protecting the calcium phosphate structure of the teeth and promoting overall dental health.
Q188. Consider the following common agricultural fertilizers:
I. Urea
II. Superphosphate
III. Potassium chloride (Muriate of potash)
IV. Sodium chloride
Which of the above identify primary NPK (Nitrogen, Phosphorus, Potassium) fertilizers?
I. Urea
II. Superphosphate
III. Potassium chloride (Muriate of potash)
IV. Sodium chloride
Which of the above identify primary NPK (Nitrogen, Phosphorus, Potassium) fertilizers?
Explanation
NPK fertilizers are those that provide one or more of the three primary macronutrients essential for plant growth: nitrogen, phosphorus, and potassium. Urea is a major source of nitrogen, superphosphate provides phosphorus, and potassium chloride, also known as muriate of potash, provides potassium. Sodium chloride, or common salt, is not used as a fertilizer as it does not provide these nutrients.
Q189. DDT (Dichloro-diphenyl-trichloroethane) was widely used globally as an:
Explanation
DDT is a potent synthetic organochlorine compound that was once widely used globally as an insecticide in both agriculture and disease control. It was particularly effective in reducing the populations of mosquitoes that carry malaria and lice that spread typhus. However, its long-term environmental persistence and harmful effects on wildlife led to widespread bans or severe restrictions on its use globally.
Q190. Most commercial liquid drain cleaners are highly caustic and rely on which strong base to dissolve clogs?
Explanation
Most commercial liquid drain cleaners contain a high concentration of sodium hydroxide, also known as caustic soda or lye. This strong base is highly effective at dissolving organic clogs, such as hair, grease, and food particles, through a process of chemical decomposition. Its caustic nature allows it to break down tough blockages quickly, though it must be handled with extreme care.Answer key for these questions
| Q | Correct answer |
|---|---|
| 181 | (c) They do not form scum in hard water |
| 182 | (a) I and II only |
| 183 | (d) Sodium benzoate |
| 184 | (a) Artificial sweetening agents |
| 185 | (c) Enhance flavor |
| 186 | (a) Antiseptics |
| 187 | (d) To neutralize the acids produced by bacteria in the mouth |
| 188 | (a) I, II and III only |
| 189 | (c) Insecticide |
| 190 | (d) Sodium hydroxide |
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.