Prelims Solution

Q. In the series AABABCABCDABCDE.., which letter appears at the 100th place?

Q. In the series AABABCABCDABCDE.., which letter appears at the 100th place?

a. G
b. H
c.  I
d. J
Correct Answer: c. I

Question from UPSC Prelims 2022 CSAT Paper

Explanation : 

In the series aababcabcdabcde , 100th letter ?

Given Series = A (1 Letter) AB (2 Letters) ABC (3 Letters) ABCD (4 Letters) ABCDE (5 Letters) …… so on up to 100th letter.
Sum of first 13 natural numbers = 1 + 2 + 3 + 4 + 5 ….. 13 = n(n+1)/2 = 13×14/2 = 91.
So, if we have to count upto 100th letter, in the last string (100 – 91) = 9 letters would be there.
Which would be – ABCDEFGHI.
So I is the correct answer.

Q. In the series AABABCABCDABCDE.., which letter appears at the 100th place? Read More »

Q. For any choices of values of X, Y and Z, the 6-digit number of the form XYZXYZ is divisible by :

Q. For any choices of values of X, Y and Z, the 6-digit number of the form XYZXYZ is divisible by :

(a) 7 and 11 only
(b) 11 and 13 only
(c) 7 and 13 only
(d) 7, 11 and 13
Correct Answer: (d) 7, 11 and 13

Question from UPSC Prelims 2023 CSAT

Explanation : 

XYZXYZ is divisible by ?

The number of the form XYZXYZ can be expressed as follows:
XYZXYZ = XYZ * 1000 + XYZ

Now, factor out 1000 from the first term:
XYZXYZ = XYZ * (1000 + 1)

Simplify the expression inside the parentheses:
XYZXYZ = XYZ * 1001

So, the number of the form XYZXYZ is equal to XYZ * 1001.

The prime factorization of 1001 is 7 * 11 * 13. Therefore, any number of the form XYZ * 1001 will be divisible by 7, 11, and 13.

So, the correct answer is (d) 7, 11, and 13. You can verify this by dividing 111111 by 7, 11, or 13 and getting a whole number as the quotient.

Q. For any choices of values of X, Y and Z, the 6-digit number of the form XYZXYZ is divisible by : Read More »

If 15X14X13x…….X3X2X1=3mXn where m and n are positive integers, then what is the maximum value of m?

Q. If 15X14X13x…….X3X2X1=3^mXn
where m and n are positive integers, then what is the maximum value of m?

a.  7
b. 6
c.  5
d. 4
Correct Answer: b.  6

Question from UPSC Prelims 2022 CSAT Paper

Explanation : 

If 15*14*13

First, let’s compute the prime factorization of 15!:
15! = 15 × 14 × 13 × 12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1
Now, let’s break down each of these factors into their prime factors:
15! = (3×5) × (2×7) × 13 × (2^2×3) × 11 × (2×5) × (3^2) × (2^3) × 7 × (2×3) × 5 × (2^2) × 3 × 2
15! = 2^11 × 3^6 × 5^3 × 7^2 × 11 × 13

We want to express this as the product of two integers, 3m and n. Since we want to maximize m, we should try to include as many factors of 3 in 3m as possible. There are 6 factors of 3 in the prime factorization of 15!, so the maximum value of m is 6.

Therefore, the maximum value of m is 6 (option b).

If 15X14X13x…….X3X2X1=3mXn where m and n are positive integers, then what is the maximum value of m? Read More »

Q. With reference to the cultural history of India, which one of the following is the correct description of the term ‘paramitas’?

Q. With reference to the cultural history of India, which one of the following is the correct description of the term ‘paramitas’?

(a) The earliest Dharmashastra texts written in aphoristic (sutra) style
(b) Philosophical schools that did not accept the authority of Vedas
(c) Perfections whose attainment led to the Bodhisattva path
(d) Powerful merchant guilds of early medieval South India

Correct Answer – (c) Perfections whose attainment led to the Bodhisattva path

Question from UPSC Prelims 2020 GS Paper

Explanation:

Paramitas and Bodhisattva for UPSC

The term ‘paramitas’ in Buddhist philosophy refers to the perfections or virtues that are cultivated as a way of purification by those aspiring to attain Buddhahood. The concept is particularly emphasized in Mahayana Buddhism and is central to the path of a Bodhisattva.

A Bodhisattva is a being who seeks Buddhahood through the systematic practice of these virtues, not just for their own liberation, but for the benefit of all sentient beings. The paramitas are considered essential qualities to be developed for the attainment of enlightenment and include generosity, morality, patience, effort, meditation, and wisdom, among others, depending on the tradition.

Thus, option (c) is the correct description of ‘paramitas’ in the context of the cultural history of India.

Q. With reference to the cultural history of India, which one of the following is the correct description of the term ‘paramitas’? Read More »

Q. If you withdraw ₹1,00,000 in cash from your Demand Deposit Account at your bank, the immediate effect on aggregate money supply in the economy will be

Q. If you withdraw ₹1,00,000 in cash from your Demand Deposit Account at your bank, the immediate effect on aggregate money supply in the economy will be

(a) to reduce it by ₹1,00,000
(b) to increase it by ₹1,00,000
(c) to increase it by more than ₹1,00,000
(d) to leave it unchanged

Correct Answer – (d) to leave it unchanged

Question from UPSC Prelims 2020 GS Paper

Explanation:

Aggregate money supply if you withdraw rs 1 lakh ?

The aggregate money supply in an economy is typically considered to include both physical currency (cash) in circulation and demand deposits (balances in bank accounts that can be accessed on-demand).

When you withdraw ₹1,00,000 in cash from your Demand Deposit Account, you are essentially converting one form of money (bank deposits) into another form of money (physical currency).

The total amount of money in the economy (the sum of physical currency and demand deposits) does not change due to this transaction. You have simply changed the composition of the money supply, not the total amount.

Therefore, the immediate effect on the aggregate money supply in the economy is to leave it unchanged.

Q. If you withdraw ₹1,00,000 in cash from your Demand Deposit Account at your bank, the immediate effect on aggregate money supply in the economy will be Read More »

Q. If another global financial crisis happens in the near future, which of the following actions/policies are most likely to give some immunity to India?

Q. If another global financial crisis happens in the near future, which of the following actions/policies are most likely to give some immunity to India?

  1. Not depending on short-term foreign borrowings
  2. Opening up to more foreign banks
  3. Maintaining full capital account convertibility

Select the correct answer using the code given below:

(a) 1 only
(b) 1 and 2 only
(c) 3 only
(d) 1, 2 and 3

Correct Answer – (a) 1 only

Question from UPSC Prelims 2020 GS Paper

Explanation:

If another global financial crisis happens ???

1. Not Depending on Short-Term Foreign Borrowings

This is a crucial strategy for any country looking to insulate itself from global financial crises. Short-term foreign borrowings can be highly volatile. In times of global financial stress, foreign investors may quickly withdraw their investments, leading to a sudden shortage of foreign currency, which can exacerbate the crisis for the borrowing country. By not depending heavily on such borrowings, a country can reduce its vulnerability to sudden stops and reversals of capital flows, which are common features of global financial crises.

2. Opening up to More Foreign Banks

While this can have benefits in terms of bringing in more capital and potentially more efficient banking services, it does not necessarily provide immunity against a global financial crisis. In fact, it could increase vulnerability in some cases. Foreign banks may quickly repatriate capital in times of global stress, exacerbating liquidity issues in the domestic market. Therefore, this option does not directly contribute to immunity against a global financial crisis.

3. Maintaining Full Capital Account Convertibility

This means allowing the free exchange of local currency for foreign currency and vice versa without restrictions. While it can encourage foreign investment and economic integration with global markets, full capital account convertibility also increases vulnerability to global financial shocks. It can lead to rapid and large-scale capital outflows during times of global financial stress, destabilizing the domestic financial system.

Therefore, the option that most directly contributes to some level of immunity against a global financial crisis for India is not depending on short-term foreign borrowings. Opening up to more foreign banks and maintaining full capital account convertibility, while having their own merits in certain contexts, do not directly offer protection against a global financial crisis and, in some scenarios, could even increase vulnerability.

Q. If another global financial crisis happens in the near future, which of the following actions/policies are most likely to give some immunity to India? Read More »

Q. Which of the following are the reasons/factors for exposure to benzene pollution?

Q. Which of the following are the reasons/factors for exposure to benzene pollution?

  1. Automobile exhaust
  2. Tobacco smoke
  3. Wood burning
  4. Using varnished wooden furniture
  5. Using products made of polyurethane

Select the correct answer using the code given below:

(a) 1, 2 and 3 only
(b) 2 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3, 4 and 5

Correct Answer – (a) 1, 2 and 3 only

Question from UPSC Prelims 2020 GS Paper

Explanation:

Factors for exposure to benzene pollution:

1. Automobile Exhaust:

Benzene is a well-known component of gasoline and is emitted in automobile exhaust. Therefore, areas with heavy traffic or enclosed spaces like garages can have higher levels of benzene pollution.

2. Tobacco Smoke:

Tobacco smoke is a significant source of benzene exposure for both smokers and those exposed to secondhand smoke. It is one of the most hazardous sources of indoor air pollution in terms of benzene.

3. Wood Burning:

Burning wood can release benzene, among other volatile organic compounds (VOCs), into the environment. This is especially relevant in homes that use wood as a primary heating source or in areas where open burning is common.

4. Using Varnished Wooden Furniture:

Varnishes and paints can contain benzene and other VOCs, especially if they are solvent-based. However, once these finishes have dried and cured, the amount of benzene they emit is significantly reduced. The risk of exposure from varnished wooden furniture is generally lower compared to direct sources like smoke or exhaust, but it can still contribute to indoor air levels of benzene, especially in newly furnished or renovated spaces.

5. Using Products Made of Polyurethane:

Polyurethane foam, used in furniture, mattresses, and various building materials, can emit VOCs. However, benzene is not typically a significant component of the emissions from polyurethane products. The primary concern with polyurethane often relates to isocyanates used in its production and other VOCs, rather than benzene specifically.

Given the analysis:

  • Automobile exhaust, tobacco smoke, and wood burning are direct sources of benzene pollution.
  • Using varnished wooden furniture can be a source, albeit less direct and typically with lower exposure levels once the varnish has cured.
  • Using products made of polyurethane is less about benzene exposure and more about other VOCs and chemicals.

Therefore, the most accurate answer, considering the directness and significance of benzene exposure, would be:

(a) 1, 2, and 3 only. This is also official UPSC Answer but other websites are saying d)

Q. Which of the following are the reasons/factors for exposure to benzene pollution? Read More »

Q. In India, the term “Public Key Infrastructure” is used in the context of

Q. In India, the term “Public Key Infrastructure” is used in the context of

(a) Digital security infrastructure
(b) Food security infrastructure
(c) Health care and education infrastructure
(d) Telecommunication and transportation infrastructure

Correct Answer – (a) Digital security infrastructure

Question from UPSC Prelims 2020 GS Paper

Explanation:

Public Key Infrastructure is used in the context of ?

The term “Public Key Infrastructure” (PKI) is used in the context of digital security infrastructure. PKI is a set of roles, policies, hardware, software, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates and manage public-key encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email. It is used to secure the identities of people, devices, and services, ensuring that communications and transactions can be trusted.

 

Q. In India, the term “Public Key Infrastructure” is used in the context of Read More »

Q. What is the importance of using Pneumococcal Conjugate Vaccines in India?

Q. What is the importance of using Pneumococcal Conjugate Vaccines in India?

  1. These vaccines are effective against pneumonia as well as meningitis and sepsis.
  2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.
  3. These vaccines have no side effects and cause no allergic reactions.

Select the correct answer using the code given below:

(a) 1 only
(b) 1 and 2 only
(c) 3 only
(d) 1, 2 and 3

Correct Answer – (b) 1 and 2 only

Question from UPSC Prelims 2020 GS Paper

Explanation:

1. These vaccines are effective against pneumonia as well as meningitis and sepsis.

This statement is true. Pneumococcal Conjugate Vaccines (PCVs) are designed to protect against pneumococcal diseases caused by Streptococcus pneumoniae, which include pneumonia, meningitis, and sepsis. These diseases can be severe and sometimes fatal, especially in young children, the elderly, and individuals with certain health conditions that compromise their immune systems.

2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.

This statement is also true. Overuse and misuse of antibiotics have contributed to the rise of antibiotic-resistant bacteria. By preventing pneumococcal diseases, PCVs reduce the need for antibiotics, thereby helping to slow down the development of antibiotic resistance.

3. These vaccines have no side effects and cause no allergic reactions.

This statement is not accurate. While PCVs are generally safe and well-tolerated, they can cause side effects and allergic reactions in some individuals, like any other vaccine. Common side effects include pain at the injection site, fever, irritability, and loss of appetite. Severe allergic reactions are rare but can occur.

Therefore, the statements 1 and 2 highlight the importance of using Pneumococcal Conjugate Vaccines in India, making option (b) the correct answer.

Q. What is the importance of using Pneumococcal Conjugate Vaccines in India? Read More »

Q. Consider the following statements: Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.

Q. Consider the following statements:

1. Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
2. A person’s genome can be edited before birth at the early embryonic stage.
3. Human induced pluripotent stem cells can be injected into the embryo of a pig.
Which of the statements given above is/are correct?

(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1, 2 and 3

Correct Answer – (d) 1, 2 and 3

Question from UPSC Prelims 2020 GS Paper

Explanation:

Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent ?

Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent. Techniques such as CRISPR-Cas9 have made it possible to edit the genome of germ cells (sperm and eggs), which can then pass these genetic changes to future generations. This approach has significant implications for eliminating genetic diseases but also raises ethical concerns.

Genome Editing at the Early Embryonic Stage

A person’s genome can be edited before birth at the early embryonic stage. Genome editing technologies like CRISPR can be used to edit the genome of embryos at the early developmental stage. This has been a subject of much debate, especially after the announcement of the birth of the first genetically edited babies in China in 2018, where CRISPR was used to edit embryos to make them resistant to HIV.

Human induced pluripotent stem cells

Human induced pluripotent stem cells (iPSCs) can be injected into the embryo of a pig. Research has been conducted where human iPSCs are introduced into the embryos of other species, such as pigs, to study the development of human organs within these animals for research and potential organ transplantation. This field is known as interspecies chimerism and has been explored as a way to potentially grow human organs in animals for transplantation, though it also faces significant ethical and technical challenges.

Q. Consider the following statements: Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent. Read More »