[DAY 19] 60 DAY RAPID REVISION (RaRe) SERIES for UPSC Prelims 2025 – GEOGRAPHY, CURRENT AFFAIRS & CSAT TEST SERIES!

Solution (c)

Statement Analysis:

Temperature inversion is a reversal of the normal behaviour of temperature in the troposphere. Under this meteorological phenomenon, a layer of warm air lies over the cold air layer.

The favourable conditions for temperature inversion are:

• Cloudless and clear sky – Loss of heat through terrestrial radiation proceeds more rapidly without any obstruction. Hence statement 1 is correct.
• Long winter night – Loss of heat by terrestrial radiation from the ground surface during the night may exceed the amount of incoming solar radiation. Hence statement 2 is incorrect.
• Dry air near the ground surface – It limits the absorption of the radiated heat from the Earth’s surface. Hence statement 3 is correct.
• The slow movement of air – It results in no transfer or mixing of heat in the lower layers of the atmosphere. Hence statement 4 is correct.
• Snow-covered ground surface – This results in a maximum loss of heat through the reflection of incoming solar radiation.

Solution (b)

Statement Analysis:

• The equatorial low-pressure belt extends from the equator to 10⁰N to 10⁰S latitudes.
• The sun shines almost vertically on the equator throughout the year. As a result, the air gets warm and rises over the equatorial region producing equatorial low pressure. Hence statement 1 is incorrect.
• The sub-polar low-pressure belts extend between 45⁰N and the Arctic Circle in the northern hemisphere and between 45⁰S and the Antarctic Circle in the southern hemisphere. Hence statement 2 is correct.
• The sub-tropical high-pressure belts extend from the tropics to 35⁰N latitudes in both hemispheres.

In the northern hemisphere, it is called the North sub-tropical high-pressure belt and in the southern hemisphere, it is called the South sub-tropical high-pressure belt. Hence statement 3 is correct.

Solution (c)

Statement Analysis:

• The trade winds are those blowing from the sub-tropical high-pressure areas towards the equatorial low-pressure belt. Hence statement 1 is correct.
• Therefore, these are confined to a region between 30°N and 30°S throughout the earth’s surface.
• They flow as the north-eastern trades in the northern hemisphere and the south-eastern trades in the southern hemisphere. Hence statement 2 is correct.
• Trade winds are descending and stable in areas of their origin (sub-tropical high-pressure belt), and as they reach the equator, they become humid and warmer after picking up moisture on their way.
• The trade winds from two hemispheres meet at the equator, and due to convergence they rise and cause heavy rainfall.

 Solution (c)

Statement Analysis:

Hence option c is correct.

Solution (c)

Statement Analysis:

• Land and sea breezes are prevalent on the narrow strips along the coasts or a lake. Hence statement 1 is correct.
• Land and sea breezes are diurnal (daily) cycles, in which the differential heating of land and water produces low and high pressures. Hence statement 2 is correct.
• During the day when a landmass gets heated more quickly than the adjoining sea or large lake; air expands and rises. This process produces a local low-pressure area on land.
• Sea breeze then develops, blowing from the water (high pressure) towards the land (low pressure).
• The sea breeze begins to develop shortly before noon and generally reaches its greatest intensity during mid-day to late afternoon. These cool winds have a significant moderating influence in coastal areas.
• At night, the land and the air above it cool more quickly than the nearby water body.
• As a result, land has high pressure while the sea has comparatively a low-pressure area.
• The gentle wind begins to blow from land (high pressure) towards the sea (low pressure). This is known as a land breeze.

Solution (d)

Statement Analysis:

The strong and rapidly moving circumpolar upper westerly air circulation in a narrow belt of a few hundred kilometres width in the upper limit of the troposphere is called a jet stream.

The significance of Jet Streams:

• They help in the maintenance of latitudinal heat balance by mass exchange of air. Hence statement 1 is correct.
• The sub-tropical jet stream and some temporary jet streams together influence Indian monsoon patterns.
• They exercise an influence on the movement of air masses which may cause prolonged drought or flood conditions. Hence statement 2 is correct.
• Polar front jets help in determining the weather because they usually separate colder air and warmer air.
• Polar front jets also play a major role in determining the path and intensity of frontal precipitation and frontal cyclones. Hence statement 3 is correct.

Solution (d)

Statement Analysis:

Atmospheric stability and instability refer to the behaviour of air in the Earth’s atmosphere. Stable air is characterized by a tendency to resist vertical motion, while unstable air is characterized by a tendency to rise and form clouds and precipitation.

The factors that influence atmospheric stability and instability are:

• Pressure: High-pressure systems are associated with stable atmospheric conditions, while low-pressure systems are associated with unstable conditions and the potential for storms and severe weather. Hence statement 1 is correct.
• Topography: The mountain ranges and other topographic features can affect atmospheric stability and instability by forcing air to rise or sink and creating areas of high and low pressure. Hence statement 2 is correct.
• Humidity: The amount of moisture in the air can affect atmospheric stability and instability, with moist air being more likely to rise and form clouds and precipitation. Hence statement 3 is correct.

Temperature: Warm air is less dense than cold air and tends to rise, while cold air is denser and tends to sink. This creates differences in pressure that can lead to the formation of clouds and precipitation. Hence statement 4 is correct.

Solution (a)

Statement Analysis:

Hence option a is correct.

Solution (a)

Statement Analysis:

• The precipitation in the form of hard-rounded pellets is known as hail. Its size ranges from 5 mm and 50 mm. Hence statement 1 is correct.
• The raindrop that evaporates before reaching the earth is known as virage.

Sleet is a frozen raindrop and refrozen melted snow. It is a mixture of snow and rain or merely partially melted snow. Hence statement 2 is incorrect.

Solution (d)

Statement Analysis:

• When the moisture is deposited in the form of water droplets on cooler surfaces of solid objects (rather than nuclei in the air above the surface) such as stones, grass blades, and plant leaves, it is known as dew.
• The ideal conditions for its formation are a clear sky, calm air, high relative humidity, and cold and long nights. Hence option d is correct.
• For the formation of dew, the dew point must be above the freezing point.

Solution (a)

Statement Analysis:

• Tropical cyclones have a thermal origin whereas temperate cyclones originate due to Coriolis force, movement of air masses, etc.
• Tropical cyclones form only on seas whereas temperate cyclones can form both on land and sea. Hence statement 1 is correct.
• In a tropical cyclone, heavy rainfall occurs but does not last beyond a few hours. If the cyclone stays in place, the rainfall may continue for many days.
• In a temperate cyclone, rainfall is slow and continues for many days, sometimes even weeks.
• Tropical cyclones are confined to 10⁰ – 30⁰ N and S of the equator whereas temperate cyclones are confined to 35⁰ – 65⁰ N and S of the equator. Hence statement 2 is incorrect.

 Solution (b)

Statement Analysis:

• When wind forces moist air landwards towards the mountain’s terrain then the mountain further lifts the moist air in an upward direction that is into the atmosphere. 
• Once the air reaches the atmosphere it cools down and undergoes a precipitation process. It is called orographic rainfall.
• The principal characteristic behind the orographic rainfall is that the windward slope gets heavy rainfall and the leeward side gets little rainfall which is known as the rain-shadow area. Hence statement 1 is incorrect.

Mountains act as an obstacle that forces the vapour to rise which leads to orographic rainfall. This rainfall is commonly seen in mountainous areas and along hills. Hence statement 2 is correct.

Solution (a)

Statement Analysis:

• The formation of convectional rainfall occurs when air is on the surface of the earth or a few metres above the surface of the earth it is heated by the sun. Hence statement 1 is correct.
• Once the air is heated it becomes lighter and further, this lighter air rises and cools down and condenses on the condensation nuclei which are present in the atmosphere. This is because only a small surface of the area is covered by converging air. 
• As soon as air converges it gets condense to form a thick cumulus cloud. As the cloud rises it becomes unstable and because of this instability cloud drops on the ground in the form of raindrops or rainfall.
• Convectional rainfall occurs usually in the summer or the hotter part of the day. Hence statement 2 is incorrect.
• The equatorial region and internal part of the continents mainly in the Northern hemisphere receive conventional rainfall.

Solution (c)

Statement Analysis:

• The urban heat island is a phenomenon in which certain pockets within a city are experiencing a higher heat load than its surrounding area. Hence statement 1 is correct.
• It is caused by buildings and houses in cities made up of concrete where the heat is trapped and not able to dissipate easily.
• Buildings in cities are often made of glass, bricks, cement, and concrete. All of them are dark-coloured materials, which attract and absorb more heat.
• For building simple urban dwellings to complex infrastructures, carbon-absorbing materials like asphalt and concrete are needed for the expansion of cities. They trap huge amounts of heat which increases the mean surface temperatures of urban areas. Hence statement 2 is correct.
• Green vegetation like plants, trees, and forests are prominent factors in regulating the incidences of urban heat islands.

Transpiration is the phenomenon that plants carry to regulate temperature. Hence statement 3 is correct.

Solution (a)

Statement Analysis:

• Rossby waves are formed when polar air moves toward the Equator while tropical air is moving poleward. Hence statement 1 is correct.
• In planetary atmospheres, they are due to the variation in the Coriolis effect (When temperature contrast is low, the speed of the jet stream is low, and the Coriolis force is weak leading to meandering) with latitude.
• Rossby waves are a natural phenomenon that can be observed in the atmosphere and oceans due to the rotation of the earth. Hence statement 2 is incorrect.
• The existence of these waves explains the low-pressure cells (cyclones) and high-pressure cells (anticyclones).

Solution (b)

Statement Analysis:

• The vertical transfer of heat by the movement of mass from one place to another is called convection.
• The air of the lower layers of the atmosphere gets heated either by the earth’s radiation or by conduction. The heating of the air leads to its expansion. Its density decreases and it moves upwards. Hence statement 1 is correct.
• The horizontal transfer of heat by the winds is called advection.
• The temperature of a place will rise if it lies on the path of winds coming from a warmer region.
• The temperature of a place will fall if it lies on the path of winds coming from a colder region. Hence statement 2 is correct.
• The transfer of heat at the zone of contact between the atmosphere and the earth’s surface is called conduction. 

When the source of heat transmits heat directly to an object through heat waves, it is known as radiation. It is the process by which solar energy reaches the earth and the earth loses energy to outer space. Hence statement 3 is incorrect.

Solution (d)

Statement Analysis:

• A line representing points of equal atmospheric pressure is called an isobar. Hence statement 1 is incorrect.

A line representing points of equal temperature is called an isotherm. Hence statement 2 is incorrect.

Solution (d)

Statement Analysis:

Frost is water vapour, or water in gas form, that becomes solid. It usually forms on objects like cars, windows, and plants that are outside in air that is saturated or filled with moisture.

Conditions for the formation of frost are:

• It develops when the surface’s temperature falls below the dew point of the surrounding air. It forms rapidly when the air is calm as the wind cannot carry away the heat from the surface, allowing it to cool more quickly. 
• Its formation and saturation of the air are more likely to occur when there is a greater value of the relative humidity, the nearer the temperature of the air to the dew point temperature. 
• It forms when the surface temperature falls below the dew point of the surrounding air during cold and long nights. On cold nights, when there is a greater temperature difference between the surface and the air, frost formation is more likely to happen. Also, longer nights give the surface more time to cool down. 
• When condensation occurs below the freezing point (0° C), i.e., when the dew point is at or below the freezing point, frost forms on cold surfaces. Except that the air temperature must be at or below freezing point, the ideal conditions for the development of white frost are the same as those for the formation of dew. 

Hence option d is correct.

Solution (a)

Statement Analysis:

The atmosphere can be divided into layers based on its temperature. These layers are the troposphere, the stratosphere, the mesosphere, and the thermosphere. A further region, beginning about 500 km above the Earth’s surface, is called the exosphere. 

• The troposphere is the atmospheric layer closest to the planet and contains the largest percentage (around 80%) of the mass of the total atmosphere. Temperature and water vapor content in the troposphere decreases rapidly with altitude. The troposphere contains 99% of the water vapor in the atmosphere. Water vapor concentrations vary with latitude. They are greatest above the tropics, where they may be as high as 3%, and decrease toward the polar regions. 

• The mesosphere is a layer extending from approximately 30 to 50 miles (50 to 85 km) above the surface and is characterized by decreasing temperatures. The coldest temperatures in Earth’s atmosphere occur at the top of this layer, the mesopause, especially in the summer near the pole. 
• The exosphere is the most distant atmospheric region from Earth’s surface. In the exosphere, an upward travelling molecule can escape to space (if it is moving fast enough) or be pulled back to Earth by gravity (if it isn’t) with little probability of colliding with another molecule. The altitude of its lower boundary, known as the thermopause or exobase, ranges from about 150 to 300 miles (250-500 km) depending on solar activity. The exosphere is a transitional zone between Earth’s atmosphere and interplanetary space. 

Hence option a is correct.

Solution (b)

Statement Analysis:

Cumulonimbus Clouds are towering or plume-shaped multi-level clouds that have an intimidating appearance. These clouds are also referred to as thunderclouds and they are the only type of clouds that can produce hail, thunder, and lightning. They are formed when there is a rapid rise or movement of warm and moist air. They can form at heights of more than 20 kilometer and are formed by the upward movement of warm, moist air. Hence option b is correct.

Solution (b)

Context:

• Built six decades ago, the canal network connected to Hirakud Dam, one of the biggest projects in eastern India, is all set to be renovated. In this context, the dam becomes important from the perspective of UPSC.

Explanation:

• Hirakud dam is built across the river Mahanadi at about 15 km upstream of Sambalpur town in the state of Odisha. Mahanadi rises from Raipur district of Chhattisgarh and flows for about 851 km before its outfall into the Bay of Bengal. Its main tributaries are the Seonath, the Jonk, the Hasdeo, the Mand, the ib, the Ong and the Tel. Hence, statement 1 is not correct.

• Hirakud dam is the longest dam in India. It is one of the first major multipurpose river valley projects started after India’s independence. It was inaugurated in the year 1957, and it was declared a Ramsar site in 2021. Hence, statement 2 is correct.

It is the longest earthen dam in the world and its length is more than 25 km. The dam forms a vast reservoir known as the Hirakud Reservoir or Hirakud Lake. It is the biggest artificial lake in Asia, with an area of 746 sq km. Hence, statement 3 is correct.

Solution (d)

Context:

• Recently, the Geographical Indications Registry in Chennai has granted the GI tag to eight products from the Assam region, including traditional food items and several unique varieties of rice beer. In this context, the names of these products and the state to which they belong become important for UPSC.

Explanation:

Bodo Jou Gwran is aunique variety of rice beer, which has the highest percentage of alcohol (about 16.11%) when compared with other varieties of rice beer made by the Bodo community. Bodo Napham is an important and favourite dish of fermented fish prepared anaerobically in a tightly sealed container in a process that requires about two-three months. Both these products belong to Assam and were recently given GI tag. Hence, option d is the correct answer.

Solution (c)

Context:

• Sammy Basso, who was the longest living survivor of the rare genetic disease progeria, recently died at the age of 28. So, the basic details about the disease becomes important for UPSC.

Explanation:

Progeria, also known as Hutchinson-Gilford progeria syndrome, is an extremely rare, progressive genetic disorder. It causes children to age rapidly. It is reported to occur in 1 in 4 million newborns worldwide. Newborns with the disorder appear to be healthy at birth but usually start to show signs of premature aging during their first one to two years of life. Hence, option c is the correct answer.

Solution (c)

Context:

• The World Health Organization (WHO) launched the Global Strategic Preparedness, Readiness and Response Plan (SPRP) which aims at reducing the burden of disease, suffering and deaths from dengue and other Aedes-borne arboviral diseases such as Zika and chikungunya, by fostering a global coordinated response. In this context, the plan becomes important from the perspective of UPSC.

Explanation:

• Recently, the Global Strategic Preparedness, Readiness and Response Plan (SPRP) to tackle dengue and other Aedes-borne arboviruses was launched by the World Health Organisation. It aims at reducing the burden of disease, suffering and deaths from dengue and other Aedes-borne arboviral diseases such as Zika and chikungunya, by fostering a global coordinated response. Hence, statement 1 is correct.

It is aligned with the Global Vector Control Response 2017–2030, a global strategy to strengthen vector control worldwide, and the Global Arbovirus Initiative, launched in 2022, which focuses on tackling mosquito-borne arboviruses with epidemic potential. Hence, statement 2 is correct.

Solution (a)

Context:

• Iran recently fired more than 180 ballistic missiles, including its hypersonic medium-range Fattah-2, in a major offensive aimed at overwhelming Israel’s air defences. In this context, prominent missiles like Fattah become important for UPSC.

Explanation:

• Fattah, which means conqueror in Farsi, is a hypersonic ballistic missile. It is equipped with a hypersonic glide vehicle (HGV) warhead that can manoeuvre and glide at hypersonic speed. It uses a liquid-fuel rocket propellant. The liquid fuel engine has the ability to adjust the thrust force. Hence, statement 1 is correct.

Fattah-2 was developed by Iran. It is a new version of its first domestically made hypersonic ballistic missile named ‘Fattah.’ It is capable of significant trajectory changes during flight to evade defence systems. While the missile can accelerate outside the Earth’s atmosphere, its aerodynamic control surfaces allow for steering within the atmosphere. Hence, statement 2 is not correct.

Solution (a)

Context:

• The DRDO recently announced the completion of the development trials of the ingeniously developed 4th Generation miniaturised Very Short Range Air Defence System (VSHORAD). In this context, basic details about VSHORAD becomes important for UPSC.

Explanation:

• Very Short-Range Air Defence System (VSHORADS) is a Man Portable Air Defence System (MANPAD) developed for neutralising low-altitude aerial threats at short ranges. The VSHORADS missile incorporates many novel technologies, such as the miniaturised Reaction Control System (RCS) and integrated avionics. Hence, statement 1 is correct.

• It has been indigenously designed and developed by DRDO’s Research Centre Imarat, Hyderabad, in collaboration with other DRDO laboratories and industry partners. The design of the missile, including launcher, has been highly optimized to ensure easy portability, and it doesn’t require a lot of personnel to operate. Hence, statement 2 is correct.

The missile system, being man-portable and specifically optimised for lightweight compared to other missile systems, can be deployed quickly in the mountains close to the Line of Actual Control, with China in Ladakh and Arunachal Pradesh. It has a range of up to 6 km. Hence, statement 3 is not correct.

Solution (b)

Context:

• The Madhya Pradesh cabinet recently approved the formation of a panel to develop a memorial and garden dedicated to Gond queen Rani Durgavati for Rs 100 crore. So, Rani Durgavati as a historical figure becomes important from the perspective of UPSC.

Explanation:

• Rani Durgavati (1524-2024) was the descendant of the famous Chandela dynasty of Mahoba. She was born on 5th October 1524 A.D. in the family of famous Chandel emperor Keerat Rai. The Chandel Dynasty is famous in Indian history for the valiant king Vidyadhar, who repulsed the attacks of Mehmood Gaznavi. Hence, statement 1 is correct.

• In 1542, she was married to Dalpatshah, the eldest son of King Sangramshah of the Gond Dynasty. Chandel and Gond dynasties got closer as a consequence of this marriage. Dalpatshah died in about 1550 A.D. As Vir Narayan was too young at that time, Durgavati took the reins of the Gond kingdom in her hands. In this way, she became the queen of the Gond kingdom of Garha-Katanga. Hence, statement 2 is correct.

In the year 1562, Akbar vanquished the Malwa ruler Baj Bahadur and annexed the Malwa with Mughal dominion. Consequently, the state boundary of Rani touched the Mughal kingdom. She is chiefly remembered for defending Gondwana against the Mughal Empire. She took on the might of the Mughal Empire with great courage and leadership. Hence, statement 3 is not correct.

 Solution (c)

Context:

• The Pakistan government recently banned the Pashtun Tahafuz Movement (PTM), a group which fights for the rights of ethnic Pashtuns, citing it as a threat to national security. In this context, the Pashtun community becomes important from the perspective of UPSC.

Explanation:

• Pashtuns, also known as “Pathans” and “Pakhtuns” are an ethnic group of people found throughout Afghanistan and Pakistan. They are the largest ethnic group of the population of Afghanistan (40-50 percent of the population) and bore the exclusive name of Afghan before that name came to denote any native of the present land area of Afghanistan. Hence, statement 1 is correct.

The Pashtuns are united primarily by a common language, Pashto (an official language of Afghanistan). They are generally able to speak Farsi (Persian), when necessary, often relying on the language in the context of trade dealings in the region. Other commonalities include Sunni Islam and a common social code (Pashtunwali) that governs both ethical behaviour and custom. Hence, statement 2 is correct.

Solution (a)

Context:

• Many leaders of both the ruling and opposition parties in Gujarat have protested against the proposed Eco-Sensitive Zones around Gir forest. In this context, information about eco-sensitive zones become important for UPSC.

Explanation:

• As per the National Wildlife Action Plan (2002-2016), issued by the Union Ministry of Environment, Forest and Climate Change, land within 10 km of the boundaries of national parks and wildlife sanctuaries is to be notified as eco-fragile zones or Eco-Sensitive Zones (ESZ). Hence, statement 1 is correct.

While the 10-km rule is implemented as a general principle, the extent of its application can vary. Areas beyond 10-km can also be notified by the Union government as ESZs, if they hold larger ecologically important “sensitive corridors.” Hence, statement 2 is not correct.

Solution (a)

Context:

• Recently, Margherita Sub-Division in Assam was officially renamed as the Co-District Commissioner Office Margherita. In this context, the concept of co-district becomes important for UPSC.

Explanation:

• Co-districts are smaller administrative units below the districts led by an officer of the rank of Assistant District Commissioner. The co-district commissioners will have powers and responsibilities similar to those of the district commissioners. Hence, statement 1 is correct.

• The objective of this first-of-its-kind initiative in the country is to take governance one step closer to people. It is expected to address the administrative challenges being faced by the administration in the districts. Hence, statement 2 is correct.

Recently, the Assam government launched this new concept of “co-district” within a district administration by doing away with the existing system of civil sub-divisions. Hence, statement 3 is not correct.

Solution (a) 

Explanation:

Option (a) is correct: The given option is based on the following lines “Due to the unconventional manufacturing of IoT devices and the vast amount of data they handle, there’s a constant threat of cyber-attacks” and “IoT security is vital for enterprises, as it includes a wide range of techniques, strategies, protocols, and actions that aim to mitigate the increasing IoT vulnerabilities of modern businesses. For those deploying IoT systems, hardware security and authentication are critical measures.” It shows that IoT needs to be secured considering its vulnerability to cyber-attacks. Also, they are vulnerable due to their large scale manufacturing and the concomitant impact on modern businesses. Hence, their security is crucial and must be taken seriously. So, it is the most rational inference of the passage. 

Option (b) is incorrect: This option mentions India, which is not discussed in the passage. So, this option is beyond the scope of the passage.  

Option (c) is incorrect: The given option seems to be correct, but it is not because the passage is not pessimistic about the future based on IoT. The author just lays down the challenges associated with this technology. So, this option is not the best rational inference. 

Option (d) is incorrect: The given option is about the implementation of IoT being easy. However, the passage is about security challenges in the context of IoT. Whether the implementation of IoT is easy or not is not discussed in the passage. This option statement is very general in nature, while the passage is very much focused on the security aspect of IoTs. Hence, this option is not the most rational inference of the passage.  

Solution (b) 

Explanation:

Option (a) is incorrect: The passage is not about India and how Big Tech companies are affecting India’s digital sovereignty. So, this option is beyond the scope of the passage.  

Option (b) is correct: The given statement captures the essence of the passage. The passage is about historical colonization and how the present big tech colonizes the world using data as seen in the lines “Colonialism has never been only about the relentless exploitation of resources for economic gain. … When Big Tech and their social divisions deploy datafication to do social good, here, too, economic, and moral ideals feed each other but differently.” These lines show that only the form of colonization has changed from using violence and force to using technology, but the mindset of exploitation is the same. So, this is the best-implied meaning of the passage. 

Option (c) is incorrect: Big Tech does data colonization as seen in the lines “When Big Tech and their social divisions deploy datafication to do social good, here, too, economic, and moral ideals feed each other but differently”. However, it is used in Global North as well as South, as seen in the lines – “A colonial rationality now applied within both Global North and Global South that underlies their business model.” Moreover, the option states that big data is being used, but it is not discussed in the passage.  

Option (d) is incorrect: Consider the lines – “When Big Tech and their social divisions deploy datafication to do social good, here, too, economic, and moral ideals feed each other but differently. For, helping vulnerable people (something unobjectionable) becomes itself a site of exploitation.” The main idea in the passage is how big tech uses data as a tool for colonization, not as a helping hand towards the people. This mindset is visible in option (b) which is the correct answer.  

Solution (a) 

Explanation:

Total volume of the 3 small cubes = 63 + 83 + 13 = 216 + 512 + 1 = 729 inch3 

Volume of the new cube formed = Total volume of the three smaller cubes = 729 inch3 Side of the new large cube = (729)1/3 = 9 inch 

Total surface area of the cube of side 9 inch = 6 × (side)2 = 6 × 9 × 9 = 486 inch2 Hence, option (a) is the right answer. 

Solution (c) 

Explanation:

Let the customers of A and B in 2021 be 100 each. 

In 2022, A lost 10% of its customers to B, but gained 20% customers from B. 

So, customers of A = 100 + 20 – 10 = 110 

And customers of B = 200 – 110 = 90 

Over the period from 2021 to 2022, the combined customer base of these two supermarkets increased by 40%. 

So, Total customers of A and B in 2022 = 140% of 200 = 1.4 × 200 = 280 

So, New customers in 2022 = 280 – 200 = 80 

In 2022, the customer base of ‘A’ constituted 50% of the total customers for the two competitors. 

So, out of 280, share of A is 50%, i.e., 50% of 280 = 140 

So, new customers that choose A = 140 – 110 = 30 

And new customers that choose B = 140 – 90 = 50 

Out of the 80 new customers, 50 inclined towards B. Required percentage = (50/80) × 100 = 62.5% Hence, option (c) is the right answer. 

Solution (c) 

Explanation:

Ramayan is moved from 9th to 18th position, i.e. its position increases by nine places (when seen from the right). Hence the place of Ramcharitmanas will also increase by 9 (when seen from the left). New place of Ramcharitmanas from the left = 9 + 9 = 18  

Hence, option (c) is the right answer. 

Alternate Method: 

Total books in the row = Position of Ramayan from the right (after interchange) + Position of 

Ramcharitmanas from the left (before interchange) – 1 = 18 + 9 – 1 = 26 New position of Ramcharitmanas from the left = 26 – 9 + 1 = 18 Hence, option (c) is the right answer.