Flash Card

LAKSHYA-75 [Day-3] Static Flash Cards for IAS Prelims 2020

Thunderstorms and Cyclones; Diseases caused by deficiency of vitamins and minerals; Cotton & Jute; Sedimentation, Decantation & Filtration; Plants; Electric cell and its types; Conduction, Convection & Radiation; Litmus; Neutralization; Rusting of Iron;
By IASToppers
March 08, 2020



How a thunderstorm becomes a cyclone?

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Answer & Enrich Your Learning:

Thunderstorms and Cyclones

  • Thunderstorms develop in hot, humid tropical areas like India very frequently.
  • The rising temperatures produce strong upward rising winds. These winds carry water droplets upwards, where they freeze, and fall down again.
  • The swift movement of the falling water droplets along with the rising air create lightning and sound. This event is called as a thunderstorm.

How a thunderstorm becomes a cyclone?

  • Before cloud formation, water takes up heat from the atmosphere to change into vapour.
  • When water vapour changes back to liquid form as raindrops, this heat is released to the atmosphere.
  • The heat released to the atmosphere warms the air around. The air tends to rise and causes a drop in pressure.
  • More air rushes to the centre of the storm. This cycle is repeated. The chain of events ends with the formation of a very low-pressure system with very high-speed winds revolving around it.
  • This weather condition is called a cyclone.
  • Factors like wind speed, wind direction, temperature and humidity contribute to the development of cyclones.

Structure of a cyclone

  • The centre of a cyclone is a calm area. It is called the eye of the storm.
  • A large cyclone is a violently rotating mass of air in the atmosphere, 10 to 15 km high.
  • The diameter of the eye varies from 10 to 30 km. It is a region free of clouds and has light winds.
  • Around this calm and clear eye, there is a cloud region of about 150 km in size. In this region there are high-speed winds (150–250 km/h) and thick clouds with heavy rain.
  • Away from this region the wind speed gradually decreases. The formation of a cyclone is a very complex process.



Stainless steel is made from iron but it does not rust. Why?

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Stainless steel is made by mixing iron with carbon and metals like chromium, nickel and manganese. That is why it does not rust.

Enrich Your Learning:

Rusting of Iron

  • If you leave a piece of iron in the open for some time, it acquires a film of brownish substance. This substance is called rust and the process is called rusting.
  • Rust is not iron. It is different from iron on which it gets deposited.
  • For rusting, the presence of both oxygen and water (or water vapor) is essential.
  • If the content of moisture in air is high, which means if it is more humid, rusting becomes faster.
  • The process of rusting can be represented by the following equation:

Iron (Fe) + Oxygen (O2, from the air) + water (H2O) → rust (iron oxide Fe2O3)

Prevention of Rusting

  • By preventing iron articles from coming in contact with oxygen, or water, or both.
  • One simple way is to apply a coat of paint or grease.
  • Another way is to deposit a layer of a metal like chromium or zinc on iron. This process of depositing a layer of zinc on iron is called galvanization.



What will be the product if you mix acid and base?

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Acid and base will give salt and water as a produce when get mixed.

Enrich Your Learning:


  • The reaction of an acid and a base is called neutralization.
  • In this reaction, the acidity of an acid is neutralized by an alkali. At the same time, the alkalinity of the alkali is neutralized by the acid.
  • A salt and water are the only products of neutralization.
  • A new substance formed called salt may be acidic, basic or neutral in nature.

Acid + Base → Salt + Water (Heat is evolved)

  • During the neutralization, the actual reaction that occurred is between one hydrogen ion H+ from the acid and one hydroxide ion, OHfrom the alkali to form one molecule of water, H2O.

For example,

Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) → Sodium chloride (NaCl) + Water (H2O)

Neutralization in Everyday Life


  • Our stomach contains hydrochloric acid. It helps us to digest food, but too much of acid in the stomach causes indigestion.
  • Sometimes indigestion is painful.
  • To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralizes the effect of excessive acid.

Ant bite

  • When an ant bites, it injects the acidic liquid (formic acid) into the skin.
  • The effect of the acid can be neutralized by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.

Soil treatment

  • Excessive use of chemical fertilizers makes the soil acidic. Plants do not grow well when the soil is either too acidic or too basic.
  • When the soil is too acidic, it is treated with bases like quick lime (calcium oxide) or slaked lime (calcium hydroxide).
  • If the soil is basic, organic matter (compost) is added to it. Organic matter releases acids which neutralizes the basic nature of the soil.

Factory wastes

  • The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms.
  • The factory wastes are, therefore, neutralized by adding basic substances.



Litmus paper, which is used to indicate the nature of a substance, is extracted from?

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Litmus is extracted from lichens.

Enrich Your Learning:


  • The most commonly used natural indicator is litmus. It is extracted from lichens.
  • It has a mauve (purple) colour in distilled water.
  • When added to an acidic solution, it turns red and when added to a basic solution, it turns blue.
  • It is available in the form of a solution, or in the form of strips of paper, known as litmus paper. Generally, it is available as red and blue litmus paper



Convection is the movement of heat through a substance by the collision of molecules. True OR False.

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Correct statement:

Conduction is the movement of heat through a substance by the collision of molecules.

Enrich Your Learning:

  • The heat flows from a body at a higher temperature to a body at a lower temperature.
  • There are three ways in which heat can flow from one object to another. These are conduction, convection and radiation.


  • The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction. Conduction transfers heat via direct molecular collision.
  • An area of greater kinetic energy will transfer thermal energy to an area with lower kinetic energy.
  • In solids, generally, the heat is transferred by conduction.


  • When a fluid, such as air or a liquid, is heated and then travels away from the source, it carries the thermal energy along. This type of heat transfer is called convection.
  • Where warm air rises at a place. The air pressure at that place is lowered. The cold air from the surrounding areas rushes in to fill its place. This sets up convection in air.
  • In liquids and gases, the heat is transferred by convection.


  • Thermal radiation generates from the emission of electromagnetic waves. These waves carry the energy away from the emitting object.
  • Thermal radiation is the direct result of random movements of atoms and molecules in matter.
  • No medium is required for transfer of heat by radiation. It can take place whether a medium is present or not.
  • From the sun the heat comes to us by radiation.



Non-rechargeable batteries are the example of which type of cell? Galvanic cells OR Voltaic cells.

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Non-rechargeable batteries are an example of Galvanic cells or Voltaic cells.

Enrich your learning:

Electric cell and its types:

  • An Electric cell or electrochemical cell consists of two electron conductors separated by an ionic conductor and linked by an electron conductor.
  • The ionic conductor is called the
  • The electron conductors separated by the electrolyte are called
  • The electron conductor used to link the electrodes is often a metal wire, such as copper wiring.

Types of Cell:

There are two fundamental types of electrochemical cell: Galvanic and Electrolytic.

  1. Galvanic cells (Voltaic cells):
  • They convert chemical potential energy into electrical energy.
  • The energy conversion is achieved by spontaneous redox reactions producing a flow of electrons.

Ex: Non-rechargeable batteries

  1. Electrolytic cells:
  • They are driven by an external source of electrical energy.
  • Electrolytic cell is any device in which electrical energy is converted to chemical energy and vice versa.
  • A flow of electrons drives non-spontaneous redox reactions.


Rechargeable batteries are examples of both types of cell: They operate as galvanic cells when they are powering a device and as electrolytic cells when they are being recharged.



Plants having leaves with reticulate venation have which type of roots? Tap root OR fibrous root?

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Plants having leaves with reticulate venation have tap roots.

Enrich your learning:


  • Plants are usually grouped into herbs, shrubs and trees based on their height, nature of stem and branches.
  • The stem bears leaves, flowers and fruits.
  • Leaf usually has a petiole and lamina.
  • The pattern of veins on the leaf is called venation. It can be reticulate or parallel.
  • Leaves give out water vapour through the process of
  • Green leaves make their food by the process of photosynthesis using carbon dioxide and water in the presence of sunlight.
  • Roots absorb water and minerals from the soil. They also anchor the plant firmly in the soil.
  • Roots are mainly of two types: tap root and fibrous root.
  • Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.
  • The stem conducts water from roots to the leaves (and other parts) and food from leaves to other parts of the plant.
  • The parts of a flower are sepals, petals, stamens and pistil.



Decantation refers to the process of?

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Decantation is a process to separate mixtures by removing a liquid layer that is free of a precipitate, or the solids deposited from a solution.

Enrich your learning:

  1. Sedimentation:
  • Sedimentation is the tendency for particles in a mixture to settle out of the fluid in which they come to rest against a barrier.
  • Sedimentation is the processes of letting suspended material settle by gravity.
  • Suspended material may be particles, such as clay or silts, originally present in the source water.
  1. Decantation:
  • Decantation is a process to separate mixtures by removing a liquid layer that is free of a precipitate, or the solids deposited from a solution.
  • The purpose may be used to obtain a decant (liquid free from particulates) or to recover the precipitate.
  • Decantation relies on gravity to pull precipitate out of the solution, so there is always some loss of product, either from the precipitate not fully falling out of the solution or from liquid remaining when separating it from the solid portion.
  1. Filtration:
  • Filtration is a physical, biological or chemical operation that separates solid matter and fluid from a mixture with a filter medium that has a complex structure through which only the fluid can pass.
  • Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the



Jute is mainly grown in which Indian States? ii) Cotton plants require which type of soil and climate?

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  • In India, jute is mainly grown in West Bengal, Bihar and Assam.
  • Cotton plants require are usually grown at places having black soil and warm climate.

Enrich your learning:


  • Cotton plants are usually grown at places having black soil and warm climate.
  • The fruits of the cotton plant (cotton bolls) are about the size of a lemon. After maturing, the bolls burst open and the seeds covered with cotton fibers can be seen.
  • From these bolls, cotton is usually picked by hand.
  • Fibers are then separated from the seeds by combing. This process is called ginning of cotton.
  • Ginning was traditionally done by hand, but these days, machines are also used for ginning.


  • Jute fiber is obtained from the stem of the jute plant.
  • It is cultivated during the rainy season.
  • In India, jute is mainly grown in West Bengal, Bihar and Assam.
  • The jute plant is normally harvested when it is at flowering stage.
  • The stems of the harvested plants are immersed in water for a few days.
  • The stems rot and fibers are separated by hand.
  • To make fabrics, all these fibers are first converted into yarns.



Beriberi disease is caused by the deficiency of which Vitamin?

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Answer: Vitamin B

Enrich your learning:

Diseases caused by deficiency of vitamins and minerals:

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