Test: Class 8 General Science NCERT Based - 2


25 Questions MCQ Test Science & Technology for UPSC CSE | Test: Class 8 General Science NCERT Based - 2


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This mock test of Test: Class 8 General Science NCERT Based - 2 for UPSC helps you for every UPSC entrance exam. This contains 25 Multiple Choice Questions for UPSC Test: Class 8 General Science NCERT Based - 2 (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Class 8 General Science NCERT Based - 2 quiz give you a good mix of easy questions and tough questions. UPSC students definitely take this Test: Class 8 General Science NCERT Based - 2 exercise for a better result in the exam. You can find other Test: Class 8 General Science NCERT Based - 2 extra questions, long questions & short questions for UPSC on EduRev as well by searching above.
QUESTION: 1

Consider the following pairs:

Which of the pairs given above is/are correctly matched?

Solution: Housefly acts as the carrier of cholera. Female Anopheles mosquito is an example of carrier of the malaria parasite (Plasmodium). Female Aedes mosquito is a carrier of the dengue virus.

QUESTION: 2

Consider the following pairs:

Which of the pairs given above is/are correctly matched?

Solution: Plant disease Causative organism Mode of transmission Lemon canker Bacteria Air Rust of wheat Fungi Air and seeds Yellowing of ladyfinger Virus Insects.

QUESTION: 3

Consider the following statements regarding food preservatives.

1. Sodium Benzoate and Sodium Metabisulfite are common food preservatives.

2. Salt, sugar, edible oil and vinegar are used as food preservatives.

Which of the statements given above is/are correct?

Solution:
  • Microorganisms contaminate food items. Preservatives are used to prevent the contamination of food items.

  • Sodium Benzoate and Sodium Metabisulfite are common food preservatives. These chemicals are used for the manufacture of jams and squash. Salt, sugar, edible oil and vinegar are used to inhibit the multiplication of microorganisms in food items.

  • For example, salt, edible oil and vinegar are used to prevent the contamination of pickles; and sugar is used to prevent the contamination of jams and squash.

QUESTION: 4

Consider the following statements regarding pasteurised milk.

1. Pasteurised milk can be consumed without boiling, because it is free of microorganisms.

2. In order to pasteurise the milk, it is first heated to a temperature of 70 degree celsius, for 15-20 minutes; and then cooled rapidly; and packaged.

Which of the statements given above is/are correct?

Solution:
  • Pasteurised milk can be consumed without boiling, because it is free from microorganisms.

  • To pasteurise the milk, it is heated up to 70 degree celsius for 15-20 seconds and then cooled rapidly; and then stored or packaged. This decreases the multiplication of microorganisms. Thus, Louis Pasteur invented this method; hence it is named after him.

QUESTION: 5

Which of the following statements is not correct, in regard to nitrogen cycle?

Solution:
  • The atmospheric nitrogen cannot be taken directly by plants and animals. Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert into compounds of nitrogen.

QUESTION: 6

Consider the following:

1. Cotton

2. PET

3. Plastic

Which of the above is/are example(s) of natural polymers?

Solution:
  • A polymer is made up of many small units. A polymer can be either natural or synthetic. Cotton is a natural polymer, called cellulose.

  • Cellulose comprises many molecules of glucose monomers. Wool, silk and leather are also examples of natural polymers. Synthetic fibres are obtained from the chemical reaction of petrochemicals.

  • Polyethylene Terephthalate is a synthetic polymer, a common example of polyester. It is used to make bottles, utensils, film, wires, and other essential products. Like synthetic fibres, plastic is also a polymer. Polythene (polyethene) is an example of plastic. Plastic takes many years to decompose, hence it is not environment friendly.

QUESTION: 7

Match the items of column 1 with column 2 and select the correct answer using the code given below.

Solution:
  • Rayon, nylon, terylene and acrylic are all examples of synthetic fibres. Rayon is also called synthetic silk.

  • It is made by the synthetic treatment of wood cellulose. It is cheaper than silk. Nylon is synthesised from coal, air and water. It is the first fully synthetic fibre. Nylon wires are more durable than steel wire.

  • Terylene is a popular polyester. Fabric made from this fibre does not get wrinkled easily. Acrylic is used to make wool, sweater, shawl and blankets.

  • Objects made of acrylic are cheaper and their maintenance is easier.

QUESTION: 8

Uniforms of firemen have a coating to make them flame resistant. Which of the following is used to make that coat?

Solution:
  • Uniforms of firemen have a coating of melamine plastic to make them flame resistant. Melamine is fire-resistant and is more heat resistant as compared to other plastics. Bakelite is a bad conductor of heat and electricity. It is used to make switches, handles of utensils, etc.

  • Polyester is a polymer made up of (poly + ester) monomers. Ester is the chemical responsible for the sweet smell of fruits. Teflon is a special plastic, which does not allow oil or water to stick on it. It is used to make the non-sticky layer on the utensils used to cook food.

QUESTION: 9

Which of the following metals remains in liquid state at room temperature?

Solution: Mercury is the metal that exists as liquid in room temperature. It is an anomalous metal. Sodium and Potassium metals are soft and can be cut with a knife.

QUESTION: 10

If copper utensils are exposed to moist air for a long time, they develop a green layer over them. Which of the following is that green substance?

Solution: When copper utensils are exposed to moist air for a long time, they develop a green layer over them. This green substance is a mixture of Copper Hydroxide [Cu(OH)2] and Copper Carbonate [CuCO3].

QUESTION: 11

Which of the following is a highly reactive metal which catches fire when exposed to air?

Solution:
  • Phosphorus, Iodine and Bromine are all non-metals. They do not generally react with water, but are highly reactive in air. Of the three, phosphorus is the most reactive non-metal. It catches fire on being exposed to air.

  • To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.Bromine is the only non- metal which exists as a liquid in room temperature. Sodium is a metal which is highly reactive in nature. It reacts rapidly with air and water.

  • A lot of energy is generated in these reactions. Therefore, it is stored in kerosene oil.

QUESTION: 12

Name the synthetic polymer that resembles natural rubber?

Solution: Neoprene (CR), also called polychloroprene or chloroprene rubber, synthetic rubber produced by the polymerization (or linking together of single molecules into giant, multiple-unit molecules) of chloroprene.

QUESTION: 13

Name the polymer that can have strong intermolecular forces?

Solution:
  • Polyester is a generalised term for any fabric or textile, which is made using polyester yarns or fibres. It is a shortened name for a synthetic, man-made polymer, which, as a specific material, is most commonly referred to as a type called polyethylene terephthalate (PET).

  • It is made by mixing ethylene glycol and terephthalic acid. That all sounds extremely scientific, but basically, polyester is a kind of plastic. What are some characteristics of polyester fabric

    1. Polyester is very durable and is resistant to many chemical

    2. This is a popular fabric in the fashion industry as it is resistant to shrinking and stretching. It is also resistant to wrinkling and abrasions

    3. The fibres used to create Polyester are very strong yet lightweight

    4. The fibres are easily dyed

    5. It retains its shape very well

    6. Polyester fabric is easy to look after and it can be washed and dried at home

    7. It is a quick drying fabric, so a popular choice for outdoors clothing

QUESTION: 14

Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?

1. Good thermal conductivity

2. Good electrical conductivity

3. Ductility

4. High melting point

Solution: Some of the most common properties of Aluminium are good thermal conductivity, malleability, light weight and high melting point which make it useful for making cooking utensils.

QUESTION: 15

Which of the following represent the correct order of decreasing reactivity?

Solution:

The decreasing order of the reactivity of the common metals is given below: Li, K, Na, Ba, Ca, Mg , Al, Mn, Zn, Fe, Ni, Sn, Pb, [H], Cu,Hg, Ag, Au,Pt

 

 

QUESTION: 16

Where was the first oil well of the world drilled?

Solution: The world’s first oil well was drilled in Pennsylvania, USA, in 1859. Eight years later, in 1867, oil was found at Makum in Assam.In India, oil is found in Assam, Gujarat, Mumbai High and in the river basins of Godavari and Krishna.

QUESTION: 17

Naphthalene balls, used to combat moths and other pests, are obtained from which of the following?

Solution: Naphthalene balls are obtained from coal tar. Coke, coal tar and goal gas are all obtained from coal.Natural gas is stored under high pressure as compressed natural gas (CNG).India has vast reserves of natural gas. Natural gas has been found in Tripura, Rajasthan, Maharashtra and in the Krishna (Godavari delta).

QUESTION: 18

Consider the following statements regarding combustion and ignition temperature?

1. Oxygen is required for the combustion of materials.Heat and light are given out in this process.

2. The lowest temperature at which a substance (fuel) catches fire is called its ignition temperature.

3. The combustion of phosphorus occurs at room temperature, in the presence of air.

Which of the statements given above is/are correct?

Solution: The way food is broken down in the human body, on reaction with oxygen, to give out energy; substances react with oxygen during combustion and give out heat and light. The lowest temperature at which a substance catches fire is called its Ignition temperature. The ignition temperature of phosphorus is so low, that it catches fire in room temperature, in the presence of air.

QUESTION: 19

Consider the following statements in context of safety matches:

1. A mixture of Antimony Trisulphide and Potassium Chlorate is applied on the heads of matchsticks.

2. The rubbing surface has powdered glass and a little white phosphorus.

Which of the statements given above is/are correct?

Solution:
  • A mixture of Antimony Trisulphide and Potassium Chlorate is applied on the heads of matchsticks. Earlier, white phosphorus was also used along with these two chemicals, but due to its harmful effects, its use was discontinued in the manufacture of safety matches.

  • The rubbing surface has powdered glass and a little red phosphorus.. When the match is struck against the rubbing surface, some red phosphorus gets converted into white phosphorus.

  • This immediately reacts with Potassium Chlorate in the matchstick head to produce enough heat to ignite Antimony Trisulphide and start the combustion.

QUESTION: 20

The job of a fire extinguisher is to cut off the supply of air, or to bring down the temperature of the fuel, or both. Consider the following statements in the context of cutting off the supply of air:

1. Water vapours, formed due to water being poured on the flame, surround the combustible material, helping in cutting off the supply of air.

2. CO2, being heavier than oxygen, covers the fire like a blanket. Since the contact between the fuel and oxygen is cut off, the fire is controlled.

Which of the statements given above is/are correct?

Solution:
  • Water cools the combustible and the water vapours formed also surround the combustible material, cutting off the supply of air. Thus, the fire is extinguished. The most common fire extinguisher is water.

  • But for fires involving electrical equipment and inflammable materials like petrol, carbon dioxide (CO2) is the best extinguisher. CO2, being heavier than oxygen, covers the fire like a blanket. Since the contact between the fuel and oxygen is cut off, the fire is controlled.

  • It does not harm the electrical equipment. CO2 can be stored at high pressure as a liquid in cylinders. When released from the cylinder, CO2 expands enormously in volume and cools down.

  • Another way to get CO2 is to release a lot of dry powder of chemicals like sodium bicarbonate (baking soda) or potassium bicarbonate. On coming near the fire, these chemicals decompose to give off CO2.

QUESTION: 21

Of the following statements, which of the following is/are correct regarding candle flames?

1. Unburnt carbon particles are present in the luminous zone of the flame.

2. The non-luminous zone of the flame has a highest temperature.

Solution:
  • The substances which vapourise on combustion, produce flame. The flame produced during the combustion of candle has three parts: non luminous zone, luminous zone and non combustible zone.

  • Unburnt carbon particles are present in the luminous zone of the flame. The non luminous zone of the candle flame has the highest temperature. It is the outermost region of the flame, which is blue in colour.

QUESTION: 22

Consider the following statements:

1. Incomplete combustion of fuels produce the poisonous gas, carbon dioxide.

2. Excessive proportion of carbon dioxide in the environment results in global warming.

3. Oxides of sulfur and nitrogen mix with rain, and result in acid rain.

Which of the above statements/statements is/are correct?

Solution:
  • Incomplete combustion of fuels produce carbon monoxide. It is an extremely poisonous gas.Combustion of most fuels gives out carbon dioxide in the environment, the excessive quantity of which results in global warming.Combustion of coal and petrol give out sulfur dioxide.

  • It is an extremely suffocating and caustic gas. Moreover, petrol engines give off gaseous oxides of nitrogen. Oxides of sulphur and nitrogen dissolve in rain water and form acids. Such rain is called acid rain. It is very harmful for crops, buildings and soil.CNG produces the oxides of sulfur and nitrogen in very small amounts.

QUESTION: 23

Assertion (A): In India, 98% of the coal is found in Gondwana rocks of the Moran region.

Reason (R): The main regions of Gondwana rocks are found in West Bengal, Jharkhand and Odisha.

Codes:

Solution:
  • Around 67 % of total commercial energy produced in India and 98% of India's total account is found in Gondwana rocks of the Moran region.

  • The main regions of Gondwana rocks are found in West Bengal, Jharkhand and Odisha. There are four types of coal found in India: Anthracite (Best quality of coal found only in Jammu & Kashmir); Bituminous (Second best quality of coal); Lignite (Found in Tamil Nadu, Rajasthan, Gujarat and Jammu & Kashmir).

  • Coal accounts for approx. 67 % of total commercial energy produced in India and 98% of India’s total account is found in Gondwana rocks of Moran region.

QUESTION: 24

The major constituent of biogas is:

Solution: Biogas comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes.

QUESTION: 25

Carbonisation is a process in which

Solution:
  • Carbonization is a slow pyrolysis process in which biomass is converted into a highly carbonaceous, charcoal-like material.

  • Typically, carbonization consists of heating the biomass in an oxygen-free or oxygen-limited environment, and reaction conditions are tailored to maximize the production of char.

  • Traditionally, charcoal production is one of the oldest chemical conversion processes known to mankind. Even today, charcoal production continues on a large scale worldwide, and is still making use—in part—of tradition charcoal kilns.

  • Furthermore, there is renewed interest in carbonization, both from a scientific and a commercial point of view, for the production and application of biochar and torrefied biomass.