UPSC CISF-AC-EXE Archives

31. In which one of the following rivers is the Majuli river island situat

In which one of the following rivers is the Majuli river island situated ?

Ganga

Godavari

Brahmaputra

Kaveri

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The correct answer is Brahmaputra.

Majuli is a large river island located in the Brahmaputra River in Assam, India. It was the world’s largest river island for a period, though its size has decreased significantly due to erosion. The island is formed by the Brahmaputra river in the south and the Kherkutia Suti, an anabranch of the Brahmaputra, joined by the Subansiri River in the north.

Majuli is culturally significant as the hub of Assamese neo-Vaishnavite culture, with numerous Satras (monasteries) located there. The island faces severe environmental challenges, primarily riverbank erosion, which has led to a substantial reduction in its area over the past few decades. Efforts are ongoing for its conservation.

32. Which one among the following is the place of confluence of the rivers

Which one among the following is the place of confluence of the rivers Alaknanda and Bhagirathi ?

Vishnuprayag

Karnaprayag

Devprayag

Rudraprayag

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The correct answer is Devprayag.

Devprayag is one of the Panch Prayag (five confluences) of the Alaknanda River. It is the confluence point where the Alaknanda River meets the Bhagirathi River. This confluence marks the point where the river officially gets the name “Ganga”.
– Vishnuprayag: Confluence of Alaknanda and Dhauliganga.
– Karnaprayag: Confluence of Alaknanda and Pindar.
– Rudraprayag: Confluence of Alaknanda and Mandakini.
– Devprayag: Confluence of Alaknanda and Bhagirathi.

The Panch Prayag are significant pilgrimage sites located along the Alaknanda River in Uttarakhand, India. These confluences are considered holy in Hinduism, marking key points in the journey of the Alaknanda before it merges with the Bhagirathi to form the main stem of the Ganges River.

33. Which one among the following is the northernmost located city of Indi

Which one among the following is the northernmost located city of India ?

Patna

Kolkata

Guwahati

Kohima

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The correct answer is Guwahati.

To determine the northernmost city among the given options, we need to compare their latitudes. Approximate latitudes are:
– Patna (Bihar): ~25.5° N
– Kolkata (West Bengal): ~22.6° N
– Guwahati (Assam): ~26.2° N
– Kohima (Nagaland): ~25.6° N

Comparing these values, Guwahati has the highest latitude (approximately 26.2° N), making it the northernmost city among the given options.

Latitudinal comparison is a standard method for determining the relative north-south position of places. It’s useful to have a general idea of the geographical location and approximate latitudes of major Indian cities, especially those mentioned frequently in geographical context.

34. The idea of Ecological Succession was first formally coined by

The idea of Ecological Succession was first formally coined by

Charles Darwin.

Clements.

Sir A. Tansley.

Emberlin.

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The correct answer is Clements.

Frederic Clements is widely credited with formulating the first comprehensive theory of ecological succession in the early 20th century. He developed the concept of succession as a directional process leading to a stable climax community, influenced by climate. His monograph “Plant Succession: An Analysis of the Development of Vegetation” (1916) was foundational in this field.

A) Charles Darwin’s work focused on evolution by natural selection, not specifically ecological succession.
C) Sir A. Tansley coined the term “ecosystem” but is not primarily credited with coining the idea of ecological succession itself, although he contributed to ecological thought.
D) Emberlin is not a figure widely recognized for coining the initial formal idea of ecological succession compared to Clements.

Clements’ monoclimax theory of succession was later challenged by other ecologists like Henry Gleason (individualistic concept) and Robert Whittaker (polyclimax theory), who proposed more complex and less deterministic views of vegetation change. However, Clements’ work laid the groundwork for the formal study of ecological succession.

35. Which one among the following is the most important reason for female

Which one among the following is the most important reason for female migration in India ?

Work/Employment

Marriage

Education

Business

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The correct answer is Marriage.

Based on census data and various demographic studies in India, marriage is the predominant reason for female migration. Social and cultural norms often lead women to move to their husband’s residence or village after marriage.
While work/employment is a significant driver for male migration, it is a less frequent primary reason for female migration compared to marriage, especially in rural-to-rural migration streams which constitute a large portion of internal migration in India. Education and business are also reasons for migration but are less significant in overall numbers for female migration compared to marriage.

The 2011 Census of India data indicates that marriage accounted for the largest share (about 66%) of female migration in the country. Work/employment was the reason for only about 2% of female migrants. This pattern highlights the strong influence of social factors on migration decisions for women in India.

36. Which one of the following is a characteristic feature of Market Garde

Which one of the following is a characteristic feature of Market Gardening ?

Farms are of very large size.

Netherlands is an example of Market Gardening.

It is well-developed in sparsely populated areas of North-West Europe.

This is practised in the areas where consumers of low income group are located.

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The correct answer is Netherlands is an example of Market Gardening.

Market gardening is a form of commercial horticulture that involves intensive cultivation of high-value crops (vegetables, fruits, flowers) on relatively small parcels of land, usually close to urban centers or markets. Key characteristics include:
– Small to medium-sized farms.
– Intensive farming practices (high labour and capital inputs per unit area).
– Focus on perishable or high-value crops.
– Proximity to markets for quick transport of produce.
– Dependence on efficient transportation and communication networks.

Let’s analyze the options:
A) Farms are typically small or medium-sized, not very large, to facilitate intensive cultivation and proximity to markets.
B) The Netherlands is renowned for its highly intensive and technologically advanced horticulture, including greenhouse production of vegetables, flowers, and plants, largely catering to both domestic and international markets. This is a classic example of market gardening (though often referred to more broadly as horticulture).
C) It is well-developed in areas near markets, which are typically densely populated urban centers, not sparsely populated areas.
D) Market gardening focuses on supplying consumers, typically in urban areas, who have the purchasing power to buy relatively higher-cost fresh produce. It’s not primarily targeted at low-income consumers.

Market gardening is often associated with truck farming in North America, where produce is transported by truck over relatively short distances to urban markets. Other regions known for significant market gardening include parts of Western Europe, coastal California, and areas surrounding major cities worldwide. The success of market gardening depends heavily on access to reliable transportation, labour, and capital, as well as market demand for fresh produce.

37. Consider a square of side length 2 m. What is the difference of the ar

Consider a square of side length 2 m. What is the difference of the areas of the circumscribed circle and the inscribed circle (in m²) ?

3π/2

π/2

2π

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The correct answer is π.

Let the side length of the square be s = 2 m.
The inscribed circle is tangent to all four sides of the square. Its diameter is equal to the side length of the square.
Radius of the inscribed circle (r_in) = s/2 = 2/2 = 1 m.
Area of the inscribed circle = π * (r_in)² = π * (1)² = π m².

The circumscribed circle passes through all four vertices of the square. Its diameter is equal to the length of the diagonal of the square.
Diagonal of the square = s * √2 = 2 * √2 m.
Radius of the circumscribed circle (r_circum) = (diagonal)/2 = (2√2)/2 = √2 m.
Area of the circumscribed circle = π * (r_circum)² = π * (√2)² = π * 2 = 2π m².

The difference of the areas = Area of circumscribed circle – Area of inscribed circle
Difference = 2π m² – π m² = π m².

For a square of side ‘s’, the radius of the inscribed circle is s/2, and the radius of the circumscribed circle is (s√2)/2 = s/√2. The ratio of the radii is (s/√2) / (s/2) = √2, and the ratio of the areas is (Area_circum / Area_in) = (π * (s/√2)²) / (π * (s/2)²) = (s²/2) / (s²/4) = 2. The area of the circumscribed circle is always twice the area of the inscribed circle for any square.

38. If a shopkeeper sells an item ‘A’ at 20% profit and item ‘B’ at 25% pr

If a shopkeeper sells an item ‘A’ at 20% profit and item ‘B’ at 25% profit, then the total profit made is ₹ 120. If he sells item ‘A’ at 25% profit and item ‘B’ at 20% profit, then the total profit made is ₹ 105. What is the sum of the cost price of items ‘A’ and ‘B’ ?

₹ 300

₹ 400

₹ 500

₹ 600

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The correct answer is ₹ 500.

Let the cost price of item ‘A’ be CA and the cost price of item ‘B’ be CB.
According to the first condition:
20% profit on A + 25% profit on B = ₹ 120
0.20 * CA + 0.25 * CB = 120 (Equation 1)

According to the second condition:
25% profit on A + 20% profit on B = ₹ 105
0.25 * CA + 0.20 * CB = 105 (Equation 2)

We want to find the sum of the cost prices, which is CA + CB.
Adding Equation 1 and Equation 2:
(0.20 * CA + 0.25 * CA) + (0.25 * CB + 0.20 * CB) = 120 + 105
0.45 * CA + 0.45 * CB = 225
0.45 * (CA + CB) = 225

Now, solve for CA + CB:
CA + CB = 225 / 0.45
CA + CB = 225 / (45/100)
CA + CB = 225 * (100/45)
CA + CB = (225/45) * 100
CA + CB = 5 * 100
CA + CB = 500

The sum of the cost price of items ‘A’ and ‘B’ is ₹ 500.

This problem can also be solved by multiplying the equations to remove decimals first and then adding them, or by using substitution or elimination methods to find CA and CB individually before summing them. For instance, multiplying equations by 100 gives:
20 CA + 25 CB = 12000
25 CA + 20 CB = 10500
Adding these yields 45(CA + CB) = 22500, leading to CA + CB = 500.

39. If the LCM and HCF of two positive integers are 18 and 3 respectively,

If the LCM and HCF of two positive integers are 18 and 3 respectively, then what is the minimum possible value of their sum ?

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The minimum possible value of their sum is 15.

For any two positive integers $x$ and $y$, the product of the integers is equal to the product of their Least Common Multiple (LCM) and Highest Common Factor (HCF): $x \times y = \text{LCM}(x,y) \times \text{HCF}(x,y)$. Also, both numbers must be multiples of their HCF.

Let the two positive integers be $x$ and $y$.
Given LCM$(x, y) = 18$ and HCF$(x, y) = 3$.
Using the property $x \times y = \text{LCM}(x,y) \times \text{HCF}(x,y)$:
$x \times y = 18 \times 3 = 54$.

Since the HCF is 3, both $x$ and $y$ must be multiples of 3. We can write $x = 3a$ and $y = 3b$, where $a$ and $b$ are positive integers.
Substituting these into the product equation:
$(3a)(3b) = 54$
$9ab = 54$
$ab = 6$.

Furthermore, the HCF of $x$ and $y$ is 3, which means HCF$(3a, 3b) = 3 \times \text{HCF}(a, b) = 3$. This implies HCF$(a, b) = 1$, i.e., $a$ and $b$ must be coprime.

We need to find pairs of positive integers $(a, b)$ such that $ab=6$ and HCF$(a, b)=1$.
Possible pairs $(a,b)$ for $ab=6$:
1. (1, 6): HCF(1, 6) = 1. This pair is valid.
If $a=1, b=6$, then $x = 3 \times 1 = 3$ and $y = 3 \times 6 = 18$.
Check: HCF(3, 18) = 3, LCM(3, 18) = 18. Correct.
Sum $x+y = 3 + 18 = 21$.
2. (6, 1): HCF(6, 1) = 1. This pair is valid.
If $a=6, b=1$, then $x = 3 \times 6 = 18$ and $y = 3 \times 1 = 3$.
Check: HCF(18, 3) = 3, LCM(18, 3) = 18. Correct.
Sum $x+y = 18 + 3 = 21$.
3. (2, 3): HCF(2, 3) = 1. This pair is valid.
If $a=2, b=3$, then $x = 3 \times 2 = 6$ and $y = 3 \times 3 = 9$.
Check: HCF(6, 9) = 3, LCM(6, 9) = 18. Correct.
Sum $x+y = 6 + 9 = 15$.
4. (3, 2): HCF(3, 2) = 1. This pair is valid.
If $a=3, b=2$, then $x = 3 \times 3 = 9$ and $y = 3 \times 2 = 6$.
Check: HCF(9, 6) = 3, LCM(9, 6) = 18. Correct.
Sum $x+y = 9 + 6 = 15$.

The possible sums of the two integers are 21 and 15.
The minimum possible value of their sum is 15.

40. The average marks of 40 students in a class is 59 and after removing t

The average marks of 40 students in a class is 59 and after removing the highest mark, the average of the remaining 39 students is 58. What is the highest mark in the class ?

100

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The highest mark in the class is 98.

The average of a set of numbers is the sum of the numbers divided by the count of the numbers. We can use the average and count to find the total sum of marks, and then find the difference between the total sums before and after removing the highest mark.

Given:
Number of students initially = 40
Average marks of 40 students = 59
Total marks of 40 students = Average $\times$ Number of students
Total marks (40 students) = $59 \times 40$.
$59 \times 40 = 2360$.

After removing the highest mark:
Number of remaining students = 39
Average marks of 39 students = 58
Total marks of 39 students = Average $\times$ Number of students
Total marks (39 students) = $58 \times 39$.
$58 \times 39 = 58 \times (40 – 1) = 58 \times 40 – 58 \times 1 = 2320 – 58 = 2262$.

The highest mark is the difference between the total marks of 40 students and the total marks of the remaining 39 students.
Highest mark = Total marks (40 students) – Total marks (39 students)
Highest mark = $2360 – 2262$
Highest mark = 98.