Search

UPSC (IAS) Prelims 2020: Important Questions & Answers on General Science Asked in Past 5 Years

Check important questions asked from the General Science section in the Previous years’ UPSC Civil Services paper. The mentioned questions are from the previous 5 years' papers (2015-2019) and are important for the candidates preparing for UPSC IAS 2020 Prelims.

Sep 11, 2020 13:18 IST
facebook IconTwitter IconWhatsapp Icon
UPSC (IAS) Prelims 2020: Important Questions & Answers on General Science Asked in Past 5 Years
UPSC (IAS) Prelims 2020: Important Questions & Answers on General Science Asked in Past 5 Years

Aspirants preparing for UPSC IAS Prelims 2020 exam must go through the important set of questions from General Science. Every year 2-3 questions are asked from the General Science section which can be either from the static syllabus or combined with a current event. All questions are given with solutions and explanations for a better understanding of the students. 

UPSC Civil Services (Prelims) 2020: Important Topics from Science & Technology Syllabus

UPSC (IAS) Prelims 2020: Important Questions on Art & Culture Asked in Past 7 Years

UPSC IAS Prelims 2020: Questions Based on General Science from 2019 Paper

Ques: Which one of the following statements is not correct?

(a) Hepatitis B virus is transmitted much like HIV.

(b) Hepatitis B, unlike Hepatitis C, does not have a vaccine.

(c) Globally, the number of people infected with Hepatitis B and C viruses are several times more than those infected with HIV.

(d) Some of those infected with Hepatitis Band C viruses do not show the symptoms for many years.

Answer: b

Explanation: The hepatitis B vaccine is a safe and effective vaccine that is recommended for all infants at birth and for children up to 18 years. The hepatitis B vaccine is also known as the first “anti-cancer” vaccine because it prevents hepatitis B, the leading cause of liver cancer worldwide.

Ques:  In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements:

  1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.
  2. H-CNG as a fuel reduces carbon dioxide and hydrocarbon emissions.
  3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.
  4. H-CNG makes the fuel less expensive than CNG.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 and 3 only

(c) 4 only

(d) 1, 2, 3 and 4

Answer: b

Explanation: hydrogen-enriched CNG (H-CNG) is a blend of hydrogen and CNG, the ideal hydrogen concentration being 18%. Hence, Statement 3 is correct.

Compared to conventional CNG, the use of H-CNG can reduce the emission of carbon monoxide up to 70%, not complete emission. Hence, statement 1 is not correct. It also reduces carbon dioxide and hydrocarbon emissions. Hence, statement 2 is correct.

H-CNG also enables up to 5% savings in fuel efficiency. H- CNG also reduces the engine’s unburned hydrocarbon emissions and speed up the process of combustion.

Ques: Why are dewdrops not formed on a cloudy night?

(a) Clouds absorb the radiation released from the Earth's surface.

(b) Clouds reflect back the Earth's radiation.

(c) The Earth's surface would have the low temperature on cloudy nights.

(d) Clouds deflect the blowing wind to ground level.

Answer: b

Explanation: Dew is a type of precipitation where water droplets form on the ground, or on objects near the ground in a process called condensation of moisture. The favorable weather elements for dew include clear skies, light wind, decent soil moisture, and low night-time dew point depressions. Dew forms when the temperature becomes equal to the dew point. This often happens first at ground level for two reasons. First, longwave emission causes the earth's surface to cool at night. Cloud cover prevents this from happening as it reflects the earth's radiation. Condensation requires the temperature to decrease to the dew point. Second, the soil is often the moisture source for the dew. Warm and moist soils will help with the formation of dew as the soil cools overnight.

Ques:  Consider the following:

  1. Carbon monoxide
  2. Methane
  3. Ozone
  4. Sulphur dioxide

Which of the above are released into the atmosphere due to the burning of crop/biomass residue?

(a) 1 and 2 only

(b) 2, 3 and 4 only

(c) 1 and 4 'only

(d) 1, 2, 3 and 4

Answer: d

Explanation: Explanation-Burning of crop residues emits traces of carbon dioxide, methane, carbon monoxide, nitrous oxide, sulfur dioxide, and particulates which affect human health.

Ques: In India, the use of carbofuran, methyl parathion, phorate and triazophos is viewed with apprehension. These chemicals are used as

(a) Pesticides in agriculture

(b) Preservatives in processed foods

(c) Fruit-ripening agents

(d) Moisturising agents in cosmetics

Answer: a

Explanation: Carbofuran, Phorate, and Triazophos are pesticides used in agriculture.

General Science Study Material for IAS

UPSC IAS Prelims 2020: Questions Based on General Science from 2018 Paper

Ques: Consider the following phenomena :

  1. Light is affected by gravity.
  2. The Universe is constantly expanding.
  3. Matter warps its surrounding space-time.

Which of the above is/are the prediction/predictions of Albert Einstein's General Theory of Relativity, often discussed in media ?

(a) 1 and 2 only

(b) 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: c

Explanation: 1. Einstein’s theory of relativity has important astrophysical implications. For example, it implies the existence of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape—as an end-state for massive stars.

  • There is ample evidence that the intense radiation emitted by certain kinds of astronomical objects is due to black holes; for example, microquasars and active galactic nuclei result from the presence of stellar black holes and supermassive black holes, respectively.
  • The bending of light by gravity can lead to the phenomenon of gravitational lensing, in which multiple images of the same distant astronomical object are visible in the sky. Hence, statement 1 is correct.

2: General relativity also predicts the existence of gravitational waves, which have since been observed directly by the physics collaboration LIGO. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe. Hence, statement 2 is correct.

3: General relativity is Einstein’s law of gravity, his Justification of that fundamental force that holds us to the surface of the Earth. Gravity, Einstein asserted, is caused by warping of space and time or space-time. Hence, statement 3 is correct.

Ques: Which of the following statements best describes "carbon fertilization"?

(a) Increased plant growth due to increased concentration of carbon dioxide in the atmosphere

(b) Increased temperature of Earth due to increased concentration of carbon dioxide in the atmosphere

(c) Increased acidity of oceans as a result of increased concentration of carbon dioxide in the atmosphere

(d) Adaptation of all living beings on Earth to the climate change brought about hr the increased concentration of carbon dioxide in the atmosphere

Answer: a

Explanation: The carbon fertilization effect suggests that the increase of carbon dioxide in the atmosphere increases the rate of photosynthesis in plants. The effect varies depending on the plant species, the temperature, and the availability of water and nutrients.

From a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide.

Ques: Consider the following statements:

  1. The Earth's magnetic field has reversed every few hundred thousand years.
  2. When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide.
  3. When living organisms originated, they modified the early atmosphere of the Earth.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: a

Explanation:  1: A change in the Earth’s magnetic field resulting in the magnetic north being aligned with the geographic south, and the magnetic south being aligned with the geographic north is called a geomagnetic reversal. Complete magnetic reversals have happened every 200,000 to 300,000 years over the past 20 million years. But that regularity hasn’t continued, as the last known reversal occurred roughly 780,000 years ago. 

2: Between 4.5 and 2.5 billion years (the Archaean and Proterozoic time), the earliest atmosphere contained carbon dioxide (CO2), methane (CH4), water vapor (H2O), carbon monoxide (CO), a little nitrogen (N), and hydrogen (H).

3: When living organisms originated, they did not affect the early atmosphere because they lacked the ability to do so. The early atmosphere of the earth was modified by solar winds. This happened not only in the case of the earth but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds

UPSC IAS Prelims 2020: Questions Based on General Science from 2017 Paper

Ques:  Consider the following statements:

  1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.
  2. Sexual transmission of Zika virus disease is possible.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Answer: c

Explanation: Statement 1:  Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). These are the same mosquitoes that spread dengue and chikungunya viruses.

Statement 2:  Zika can be passed through sex from a person who has Zika to his or her partners. Zika can be passed through sex, even if the infected person does not have symptoms at the time.

Ques: The terms 'Event Horizon', 'Singularity', `String Theory' and 'Standard Model' are sometimes seen in the news in the context of

(a) Observation and understanding of the Universe

(b) Study of the solar and the lunar eclipses

(c) Placing satellites in the orbit of the Earth

(d) Origin and evolution of living organisms on the Earth

Answer: a

Explanation: Singularity and event horizons are related to Black Holes. The standard model of physics tries to explain universal phenomena. String theory is used in the context of quantum physics that is used to understand quantum phenomena.

UPSC IAS Prelims 2020: Questions Based on General Science from 2016 Paper

Ques: Which of the following statements is/are correct?

  1. Viruses can infect
  2. bacteria
  3. fungi
  4. plants

Select the correct answer using the code given below.

(a) 1 and 2 only

(b) 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: d

Explanation: Viruses are known to infect almost any kind of host that has living cells. Animals, plants, fungi, and bacteria are all subject to viral infection.

Ques: In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index?

  1. Carbon dioxide
  2. Carbon monoxide
  3. Nitrogen dioxide
  4. Sulfur dioxide
  5. Methane

Select the correct answer using the code given below.

(a) 1, 2 and 3 only

(b) 2, 3 and 4 only

(c) 1, 4 and 5 only

(d) 1, 2, 3, 4 and 5

Answer: b

Explanation: Air Quality Index doesn’t include carbon dioxide and methane.

UPSC IAS Prelims 2020: Questions Based on General Science from 2015 Paper

Ques: H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases?

(a) AIDS

(b) Bird flu

(c) Dengue

(d) swine flu

Answer: d

Explanation: Influenza A (H1N1) virus is the most common cause of human influenza (flu). In June 2009, the World Health Organization (WHO) declared the new strain of swine-origin H1N1 as a pandemic. This strain is often called swine flu by public media.

Ques: With reference to ‘fuel cells’ in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements :

  1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
  2. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
  3. Fuel cells produce electricity in the form of Alternating Current (AC).

Which of the statements given above is / are correct?

(a) 1 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: a

Explanation: The purpose of a fuel cell is to produce an electrical current that can be directed outside the cell to do work, such as powering an electric motor or illuminating a light bulb or a city.

One great appeal of fuel cells is that they generate electricity with very little pollution–much of the hydrogen and oxygen used in generating electricity ultimately combine to form a harmless byproduct, namely water along with releasing heat.

A single fuel cell generates a tiny amount of direct current (DC) electricity. In practice, many fuel cells are usually assembled into a stack.

If alternating current (AC) is needed, the DC output of the fuel cell must be routed through a conversion device called an inverter.

Ques: In the context of modern scientific research, consider the following statements about ‘IceCube’, a particle detector located at South Pole, which was recently in the news :

  1. It is the world’s largest neutrino detector, encompassing a cubic kilometre of ice.
  2. It is a powerful telescope to search for dark matter
  3. It is buried deep in the ice.

Which of the statements given above is/are correct?

  1. a) 1 only
  2. b) 2 and 3 only
  3. c) 1 and 3 only
  4. d) 1, 2 and 3 only

Answer: d

Explanation: IceCube is a particle detector at the South Pole that records the interactions of a nearly massless subatomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma-ray bursts, and cataclysmic phenomena involving black holes and neutron stars.

The IceCube telescope is a powerful tool to search for dark matter and could reveal the physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

It is buried beneath the surface, extending to a depth of about 2,500 meters. Burying it deep in ice is important to enhance the precision of the detector. 

UPSC Civil Services (IAS) Prelims 2020: Subject-wise Study Material for Complete Preparation

 

 

 



Related Stories