UPSC CSE Prelims Paper 2 (CSAT) Mock Test - 2 Free Online Test 2026

Assumption 1 is incorrect. The passage mentions, “In this regard, Waste Heat constitutes a substantial amount of
energy in many core sectors such as iron and steel, cement and power plants.” So, we can assume that a substantial
amount of energy is wasted as heat, but we cannot quantify the exact amount in percentage terms. So, it is an
incorrect assumption.
Assumption 2 is incorrect. The passage mentions, “To support efforts towards sustainable growth of the economy,
the reuse of waste heat generated by industries for electricity generation has tremendous potential.” However, we
cannot assume that it will increase the profitability of industries. Such an energy may be cheaper or more expensive.
Also, the passage is not specific to Indian companies. Therefore, this assumption is incorrect.

•  Statement 1 is correct. The Waste Heat Recovery method will ensure electricity generation from waste heat that will reduce the usage of fossil fuels. It is evident from the lines, “One of the prime measures to decarbonize industries, especially steel and cement is to improve the efficiency of the overall process. ..... Waste Heat Recovery is a method of recycling and re-using the heat that is escaping the industrial processes after useful work is accomplished.” So, it is a correct statement.
• Statement 2 is correct. The passage mentions, “To support efforts towards sustainable growth of the economy, the reuse of waste heat generated by industries for electricity generation has tremendous potential.” The passage clearly says that this method will help in moving towards sustainable growth of the economy. So, it is a correct statement.
• Statement 3 is incorrect. The passage does not mention anything about the reduction in equipment size. This statement is beyond the scope of the passage.
• Statement 4 is incorrect. The passage does not mention anything about the reduction in emission of toxic liquid chemicals due to Waste Heat Recovery. This statement is beyond the scope of the passage.

[(4/5) of (4/5) ÷ (4/5)] / [(4/5) ÷ (4/5) of (4/5)]
= [(16/25) ÷ (4/5)] / [(4/5) ÷ (16/25)]
= [(16/25) × (5/4)] / [ (4/5) × (25/16)]
= (4/5) / (5/4)
= 16/25
Hence, option (b) is the correct answer.

Let A = 100

From statement 1:
45% of A + B = 125% of B
Or (45/100) × 100 + B = (125/100) × B
Or 45 + B = 5B/4
Or (5B-4B)/4 = 45
Or B = 45×4
Or B = 180
From statement 2:
20% of A + C = 125% of C
Or (20/100) ×100 + C = (125/100) × C
Or 20 + C = 5C/4
Or (5C-4C)/4 = 20
Or C = 20×4
Or C = 80
Therefore, A = 100, B = 180 and C = 80
So, B > A > C (A is less than B, but greater than C)
Hence, option (b) is the correct answer.

Given Series: MEDIUM, NGDIUM, NGGMUM, ?

The pattern of the series is as follows:

The pattern followed here is: 9 + 6 → (9×9) + (9×6) = 81 + 54 = 135
13 + 7 → (13×13) + (13×7) = 169 + 91 = 260
7 + 12 → (7×7) + (7×12) = 49 + 84 = 133
10 + 11 → (10×10) + (10×11) = 100 + 110 = 210
18 + 15 → (18×18) + (18×15) = 324 + 270 = 594
Hence, option (a) is correct.

According to the question,

Aman selected an expensive black sport shoes. So, he must have purchased a pair of shoes of Puma. Hence, option (c) is the correct answer.

Statement 1: If the sum of the digits of n is divisible by 3, it means that n is divisible by 3. For example, the number 123 is divisible by 3. The sum of its digits = 1 + 2 + 3 = 6, which is also divisible by 3. Therefore, statement 1 alone is sufficient to answer the question.

Statement 2: If the difference between the last two digits of n is divisible by 3, it does not necessarily mean that n is divisible by 3. For example, the number 25 is not divisible by 3, even though the difference between its last two digits (5 - 2 = 3) is divisible by 3. While the number 30 is divisible by 3, and the difference between its last two digits (3 - 0 = 3) is also divisible by 3. Therefore, statement 2 alone is not sufficient to answer the question.

Hence, option (a) is the correct answer.

Given Series: A, P, E, S, I, Y, O, H, ?, ?
The series given above consists of two series: First series: A, E, I, O, ?
In this series, vowels are written in ascending order. So, the next term will be U.
Second series: P, S, Y, H, ?
P + 3 = S
S + 6 = Y
Y + 9 = H
? = H + 12 = T
Thus, missing letters are U and T. Hence, option (c) is correct.

37.5% = 3/8
Let the total number of students in the school be 80x.
So, the number of girls in the school = 80x × 3/8 = 30x
And, the number of boys in the school = 80x - 30x = 50x
80% of the girls and 70% of the boys participated in annual sports of the school. So, the number of girls who did not participate in annual sports = 30x × (100 – 80)% = 30x × (20/100) = 6x
And the number of boys who did not participate in annual sports = 50x × (100 – 70)% = 50x × (30/100) = 15x
otal number of students who did not participate in annual sports = 6x + 15x = 21x
Required percentage = (21x/80x) × 100 = 26.25%

Hence, option (d) is correct.

M = 32y + 20y an + bn is always divisible by (a + b) when n is odd.
If y is odd, then 32y + 20y is exactly divisible by (32 + 20), i.e. 52. So, M is exactly divisible by 52.
As M is divisible by 52, it must also be divisible by its factors: 2, 4, 13 and 26.
Though M need not be divisible by 6.
Hence, option (b) is correct.

4⁶⁸/192 = 2^2×68 / (64×3)
= 2¹³⁶ / (2⁶×3) 
= 2¹³⁰/3    (in the end we will multiply the answer with 26)
2¹/3→ Remainder is 2
2²/3 →Remainder is 1
2³/3 →Remainder is 2  …………… and so on.
So, when power is odd, we get remainder 2.
& when power is even, we get remainder 1.
Therefore, in case of 2¹³⁰/3 we will get remainder 1.
Required Remainder = 1×2⁶ = 64

Hence, option (c) is the correct answer.

Total number of apples in the box = 15

Number of ways of choosing 4 apples from these 15 apples = 15C4 = 15! / (4! × 11!) = (15×14×13×12) / (4×3×2) = 1365

Number of ways of choosing 4 rotten apples from 5 rotten apples = 5C4 = 5! / (4! × 1!) = 5

So, Required probability = 5/1365 = 1/273

Hence, option (a) is correct.

Let diagonal of the square be d units.
Area of square = (1/2) d² If diagonal of the square is reduced by half, then the new area of the square = (1/2) × (d/2)² = (1/8) d² So, reduction in the area of the square = (1/2)d² – (1/8)d² = (3/8) d²
The percentage by which the area of that square gets reduced = [{(3/8)d²} / {(1/2)d²}] × 100 = 75% Hence, option (d) is correct.

Option (a) is incorrect. The passage only says that the rise in technological innovations has corresponded with the rise in the computational capabilities of computers. It is nowhere mentioned that this increase in computational capability of computers is due to semiconductors. So, as per the passage, it is an incorrect statement.

Option (b) is incorrect. The passage mentions, “However, its ability to self-implement instructions and carry out these functions based on its training presents us with unique ethical considerations applicable to the use of AI systems in various capacities.” The author talks about ethical considerations which could be related to potential risks. This makes this answer option close, even though the author has not delved into the regulatory aspects. Let’s put it on hold and consider other options.

Option (c) is incorrect as option (a) is incorrect.

Option (d) is correct. The sentence, “These algorithms are trained on massive datasets, i.e., training datasets, which provide it with a certain amount of input information and output” clearly reflects the role of advancements in computational power in the emergence of AI. And the line, “presents us with unique ethical considerations applicable to the use of AI systems in various capacities” highlights the concerns associated with AI. So, this answer option aptly captures the critical message of the passage.

• Inference 1 is incorrect. The passage mentions “Many argue that rapid technological change will raise agricultural yields so much by late this century that any reduction caused by global warming would easily be more than offset. But technological change is a false panacea for several reasons.” These lines clearly show that in the future technology may not solve the issue of reduced yield because of global warming. So, the given inference is not correct.
• Inference 2 is correct. This answer option is close. The passage mentions, “It also seems quite likely that a sizable share of land will be shifted to the production of biomass for ethanol fuel.” This line reflects that in future cropping land could be diverted to meet fuel requirements. This might adversely affect food security. It won’t be incorrect to say that ethanol production could probably become a roadblock for food security in future. Let’s keep this answer option on hold and consider the next option.
• Inference 3 is incorrect. The passage mentions, “Although rising agricultural prices might provide incentives that would slow or reverse this decline, such a response is not assured.” This line shows that rising prices might provide incentives which can slow down the reduction of yield, but that is not certain. So, as per the information given in the passage, this inference is not correct. Since, statements 1 and 3 are incorrect, options (a), (c) and (d) can be ruled out. Option (b) is the most appropriate answer.

• Inference 1 is incorrect. The passage mentions “Many argue that rapid technological change will raise agricultural yields so much by late this century that any reduction caused by global warming would easily be more than offset. But technological change is a false panacea for several reasons.” These lines clearly show that in the future technology may not solve the issue of reduced yield because of global warming. So, the given inference is not correct.
• Inference 2 is correct. This answer option is close. The passage mentions, “It also seems quite likely that a sizable share of land will be shifted to the production of biomass for ethanol fuel.” This line reflects that in future cropping land could be diverted to meet fuel requirements. This might adversely affect food security. It won’t be incorrect to say that ethanol production could probably become a roadblock for food security in future. Let’s keep this answer option on hold and consider the next option.
• Inference 3 is incorrect. The passage mentions, “Although rising agricultural prices might provide incentives that would slow or reverse this decline, such a response is not assured.” This line shows that rising prices might provide incentives which can slow down the reduction of yield, but that is not certain. So, as per the information given in the passage, this inference is not correct. Since, statements 1 and 3 are incorrect, options (a), (c) and (d) can be ruled out. Option (b) is the most appropriate answer.

• Option (a) is incorrect. The passage mentions, “But technological change is a false panacea for several reasons.” Technology is not the focus of the passage. Author is drawing attention towards the precarious balance between supply and demand when it comes to food, and various challenges that may further deteriorate this balance. Hence, this is not the best message of the author.
• Option (b) is correct. The passage mentions “Global food demand is expected to approximately triple by the 2080s because of the higher world population and higher incomes. It also seems quite likely that a sizable share of land will be shifted to the production of biomass for ethanol fuel. As a result, there is a rather precarious balance between supply and demand, which would be seriously worsened by a major adverse shock from global warming.” These lines show that food and fuel demand is increasing, and global warming is posing a challenge. So, there is a need to come up with some solutions to address the given challenges. Therefore, this statement best reflects the message of the author.
• Option (c) is incorrect. The given statement is not correct because it only partially covers the concerns of the author. The author has focused on both supply and demand sides while talking about the precarious balance between food supply and demand. In the lines, “Second, even if there is no further slowdown, there is likely to be a close race between rising food demand and rising output. Global food demand is expected to approximately triple by the 2080s because of the higher world population and higher incomes.” he talks about the challenges on the demand side too. Also, the issue of malnutrition in developing countries has not been discussed in the passage.  Therefore, this statement is not correct.
• Option (d) is incorrect. The given statement is not correct, because the context of organic farming and population control has not been covered in the passage. So, this cannot be the best message of the author. 

The person spent 9 hours in the journey, but gained 1 day, i.e. 24 hours. Hence, he will reach the destination on 5 P.M. of 1st May + (9 – 24) hours, i.e. 2 A.M. of 1st May.  

So, option (c) is the correct answer.

Some of the possible Venn diagrams have been shown below: 

We can conclude that “No capital is a city” is not definitely true.
Also, “Some cities are capitals” is not definitely true.
But one of these conclusions must be true.
Hence, option (b) is correct.

• From the table for March:
  • Sunflowers = 96
  • Lilies = 80
  • Roses = 118

• Sum = 96 + 80 + 118 = 294

• Number of flower‐types = 3

• Average = 294 ÷ 3 = 98

Answer: 98

Only two employees have salary less than C. The number of employees having salary higher than C is less than the number of employees having salary higher than B. So, two cases are possible.

The number of employees having salary higher than B is equal to the number of employees having salary less than E. So, we get:

Now, F earns a salary of Rs. 15000, which is not higher than the salary of either D or A. So, we get:

A or D do not earn the highest salary. So, we can eliminate Case 1. The number of employees having salary higher than A is an even number. So, we get: 

E > D > A > C > F > B

Only two employees have salary less than C. The number of employees having salary higher than C is less than the number of employees having salary higher than B. So, two cases are possible.

The number of employees having salary higher than B is equal to the number of employees having salary less than E. So, we get:

Now, F earns a salary of Rs. 15000, which is not higher than the salary of either D or A. So, we get:

A or D do not earn the highest salary. So, we can eliminate Case 1. The number of employees having salary higher than A is an even number. So, we get: 

E > D > A > C > F > B

It is given that salary of F is Rs. 15000, So B’s salary must be less than Rs. 15000, while C’s salary must be more than Rs. 15000. So, the statement “Salary of B can be Rs. 16000” cannot be true under any circumstances. 

Only two employees have salary less than C. The number of employees having salary higher than C is less than the number of employees having salary higher than B. So, two cases are possible.

The number of employees having salary higher than B is equal to the number of employees having salary less than E. So, we get:

Now, F earns a salary of Rs. 15000, which is not higher than the salary of either D or A. So, we get:

A or D do not earn the highest salary. So, we can eliminate Case 1. The number of employees having salary higher than A is an even number. So, we get: 

E > D > A > C > F > B 

• Statement 1 is incorrect: The passage mentions, “Raman discovered that when a stream of light passes through a liquid, a fraction of the light scattered by the liquid is of a different colour”. It only talks about light in general, and does not specifically mention the ultraviolet spectrum. Hence, it is not a correct statement.
• Statement 2 is incorrect: The passage states, “…when a stream of light passes through a liquid, a fraction of the light scattered by the liquid is of a different colour”. It does not mention whether the scattering is complete or partial. Hence, it is not a correct statement.
• Statement 3 is incorrect: The passage says, “One of the things that scientists look at when light is scattered is if the particle it interacts with is able to change its energy”. It implies that there is a change in the energy of the light – it could be increase or decrease in energy. Hence, it would be incorrect to talk about decrease only.
• Statement 4 is correct: According to the passage “The Raman Effect is when the change in the energy of the light is affected by the vibrations of the molecule or material under observation, leading to a change in its wavelength”.
• This implies a change in wavelength of light when it is affected by molecular vibrations. Hence, it is a correct statement.

Statement 1 is incorrect. The passage clearly states, “The Raman Effect is when the change in the energy of the light is affected by the vibrations of the molecule or material under observation”. The change actually happens in reality, and is affected by vibrations at molecule or material level. Therefore, it would be incorrect to say that change in energy of light is just a delusion.  

Statement 2 is incorrect. The passage only mentions, “The Raman Effect was the discovery which won physicist Sir CV Raman his Nobel Prize in 1930”. It does not say that he was the first Indian to win a Nobel for science. Hence, it is not a correct statement. 

• Statement 1 is correct: The passage mentions, “Traditional fire burning practices or ‘cultural burns’ by indigenous Australians can help protect the iconic koala, new research by the University of the Sunshine Coast has found”. Hence, it is a correct statement.
• Statement 2 is incorrect: The passage says, “The ‘cultural burns’ were found to be cooler, lower and slower than ‘hot fires’, according to a statement by the university. Such fire activity encouraged the regeneration of suitable native plants”.  The passage does not mention that it is antithetical (unsuitable) to alien plant species.  It only says that these fires favour certain native plants. Hence, it is not a correct statement.
• Statement 3 is correct: The passage states, “The ‘cultural burns’ were found to be cooler, lower and slower than ‘hot fires’, according to a statement by the university” and “The research results showed that there were no negative impacts on the densities or stress levels of the animals during or after the traditional burning method was used”. This clearly implies that cultural burns are relatively better than hot fires and have less negative impact on wildlife. Hence, it is a correct statement.
• Statement 4 is correct: The passage states, “The United Nations had taken note of burning practices and techniques of indigenous peoples around the world as a method to control wildfire incidents in a report last year on increasing incidences of fires globally”. Hence, cultural burns can be leveraged to control wildfires.

• Statement 1 is correct: The passage clearly states, “The ‘cultural burns’ were found to be cooler, lower and slower than ‘hot fires’, according to a statement by the university. Such fire activity encouraged the regeneration of suitable native plants”. Hence, it is correct to say that some fire activities may facilitate plant regrowth.
• Statement 2 is incorrect: The passage says, “Traditional fire burning practices or ‘cultural burns’ by indigenous Australians can help protect the iconic koala”. It nowhere mentions that it is found only among the indigenous people of Australia. There could be other communities also who practice such traditional fire burning. Hence, it is not a correct statement.

The 3-digit numbers that leave a remainder of 5 when divided by 7 are:
103, 110, 117, ………….., 999 
The given terms are in A.P., with a common difference of 7.

n^th term, an = a + (n – 1) d
Here, a = 103, a_n = 999,d = 7
So, 999 = 103 + (n – 1)7
Or (n – 1)7 = 999 – 103 = 896
Or (n – 1) = 896/7 = 128
Or n = 128 + 1 = 129
So, the total number of such terms is 129.

Sum of an AP = [(First term + Last term)/2] × number of terms So, Sum of all the 3-digit numbers that leave a remainder of 5 when divided by 7 = [(103 + 999)/2] × 129 = 71079.  Hence, option (a) is correct.

36 km/hr = 36 × 5/18 m/sec = 10 m/sec
45 km/hr = 45 × 5/18 m/sec = 12.5 m/sec
So, their relative speed = 10 + 12.5 = 22.5 m/sec
Time taken by them to meet each other = Length of the bridge / Relative speed = 315/22.5 = 14 seconds

Hence, option (c) is correct.