UPSC Prelims 2026 · CSAT (Paper II): Which of the following statements reflect the logical and rational inferences that can be…
Read the passage
When SARS-CoV-2 was first detected in 2019, it was a truly novel virus for the world. At that time, no one in the world had been exposed to SARS-CoV-2 or had specific immunity against it. In contrast, people across the world have been exposed to HMPV for decades and the virus is well-studied. HMPV and SARS-CoV-2 belong to two very different virus families with fundamentally different characteristics and epidemiology, with strong seasonality seen in HMPV, unlike SARS-CoV-2. Both viruses cause different severity of symptoms, particularly over the long term, and the affected population segments do not fully overlap. In general, HMPV causes milder illness with deaths being very rare and with no long-term post-viral symptoms.
Which of the following statements reflect the logical and rational inferences that can be drawn from the passage?
- 1. HMPV has, historically, had longer documentation of studies when compared with SARS-CoV-2.
- 2. The two viruses are different from each other and this results in markedly different outcomes amongst those affected.
- 3. Long-term impacts of the two viruses are dissimilar and this is an important differentiator between them.
- 4. One of the common factors between the two viruses is seasonal specificity.
Select the answer using the code given below.
Answer (b) & explanation
Inferences 1, 2 and 3 follow (b). Step 1: HMPV has been around "for decades" and is "well-studied", while SARS-CoV-2 was new in 2019. So HMPV has a longer record of study (1). Step 2: the viruses are "fundamentally different" and cause different severity, so outcomes differ (2). Step 3: severity differs "particularly over the long term"; HMPV has no long-term after-effects. So long-term impact is a key difference (3). Statement 4 fails: seasonality is seen in HMPV "unlike SARS-CoV-2", so it is a difference, not a common factor. Options (a), (c) and (d) fail.
Tip: "unlike" signals a difference. Do not turn it into a similarity.
Answer as per the official UPSC answer key.
Same theme in UPSC Mains
- MAINS UPSC Mains 2026 · Essay · Q1Oxymorons reflect the ironies of life.
- MAINS UPSC Mains 2026 · GS Paper II · Q6Does India's tribal development policy reflect the aspirations for a socially grounded and equity-based governance? Justify your answer.
- MAINS UPSC Mains 2026 · GS Paper I · Q5“Tundra regions are ecologically fragile but economically important.” Examine this statement critically.
Related questions from other years
Read the passage
How is deflation done? Most countries use a method called ‘double deflation’, where input and output prices are deflated separately. Consider a manufacturer importing oil for use in production. If oil prices fall, output prices do not and quantities remain the same, real value added should not change. But if the same deflator is used for inputs and outputs, as in India, it would look as if the manufacturer had become more productive.
Which of the following statements is/are correct?
- 1. Real value should not change in the instance of static output cost and unchanged quantities against falling oil prices.
- 2. Deflators are to be used separately for inputs and outputs, and this is a practice universally adopted by all economies.
Select the answer using the code given below.
Answer (d) & explanation
Neither statement is correct (d). Step 1: the passage says if oil prices fall while output prices and quantities stay the same, real value added should not change. Statement 1 changes this to "real value" and "static output cost", which distorts the idea. So 1 is not correct as worded. Step 2: statement 2 says separate deflators are used "universally" by all economies. But the passage says India uses the same deflator for both. So 2 is false. Step 3: options (a), (b) and (c) fail.
Tip: in economic passages, exact terms matter: "value added" is not "value", and "price" is not "cost". "Universally" is disproved by a single exception, here India.
Answer as per the official UPSC answer key.
P, Q, R, S and T are ranked 1 to 5 (not necessarily in that order). The rank of P is 4, the rank of Q is not 5, the rank of R is 1, the rank of S is not 2, the rank of T is not 3. Then which of the following is/are correct?
- I. If the rank of S is 3, then that of T is 2.
- II. If the rank of Q is 3, then that of T is 5.
Select the answer using the code given below.
Answer (d) & explanation
Neither statement is correct (d). Step 1: P = 4 and R = 1 are fixed. Ranks 2, 3 and 5 remain for Q, S and T, with rules: Q is not 5, S is not 2, T is not 3. Step 2: statement I: if S = 3, then Q and T share 2 and 5. Q cannot be 5, so Q = 2 and T = 5, not 2. I is wrong. Step 3: statement II: if Q = 3, then S and T share 2 and 5. S cannot be 2, so S = 5 and T = 2, not 5. II is wrong. Options (a), (b) and (c) fail.
Tip: fix the known ranks first, then apply each "if" condition and let the "not" rules decide the rest. Write the small table on paper.
Answer as per the official UPSC answer key.
How many times does 5 appear in all two-digit positive integers?
Answer (b) & explanation
The digit 5 appears 19 times (b). Step 1: 5 in the tens place: 50, 51, …, 59 = 10 times. Step 2: 5 in the units place: 15, 25, 35, 45, 55, 65, 75, 85, 95 = 9 times (05 is not a two-digit number). Step 3: total = 10 + 9 = 19. The number 55 has two 5s, and both are counted. Option (a), 18, counts 55 once. Options (c) and (d) wrongly add 05 or 5.
Tip: count place by place. The question asks how many times the digit appears, not how many numbers contain it (that would be 18).
Answer as per the official UPSC answer key.
An alloy P contains 20% copper and 80% zinc by weight. Another alloy Q contains 60% copper and 40% zinc by weight. A third alloy R is to be prepared from P and Q so that it contains equal amount of copper and zinc. In what ratio, amounts of P and Q be mixed in order to get R?
Answer (a) & explanation
P and Q must be mixed in the ratio 1 : 3 (a). Step 1: "equal copper and zinc" means R is 50% copper. Step 2: use alligation on copper: P has 20%, Q has 60%, and the mix needs 50%. P : Q = (60 − 50) : (50 − 20) = 10 : 30. Step 3: simplify to 1 : 3. Check: 1 kg P gives 0.2 kg copper; 3 kg Q gives 1.8 kg; total 2 kg copper in 4 kg = 50% ✓. Option (b) reverses the ratio. Options (c) and (d) fail.
Tip: in alligation, the amount of each item is the distance of the other item from the mean. Always check with a quick calculation.
Answer as per the official UPSC answer key.