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UPSC CSAT Simplified | CSAT getting easier? Let’s find out — Practice Set 4 for Prelims 2025

Practice makes you perfect—whether it's comprehension, reasoning, or quant! Here’s your Week 4 CSAT practice test, expertly crafted by Mudit Gupta, to help you identify weak areas and strengthen them as UPSC Prelims 2025 approaches.

You must start practicing CSAT now in a balanced manner. Are you struggling with comprehension, reasoning, or maths? Identify your weak area and focus on improving it with this CSAT Practice Set 4, as UPSC Prelims 2025 approaches.

Written by: Manas Srivastava

5 min readNew DelhiMar 2, 2025 12:56 PM IST First published on: Mar 2, 2025 at 12:56 PM IST

Dear UPSC aspirants,

We continue with our weekly practice of CSAT questions. Let’s try out some questions from CSAT Practice Set 4 and sharpen your skills as UPSC Prelims 2025 approaches. If you haven’t yet, don’t forget to check out CSAT Practice Set 1 (click here), Practice Set 2 (click here), and Practice Set 3 (click here) for more prep.

UPSC CSAT Practice Set 4

—Mudit Gupta

QUESTION #1

An international team of researchers recently conducted an experiment where they injected a mixture of nitrogen oxides and water into porous sandstone formations deep underground. Over time, the acidic solution reacted with the minerals in the sandstone, releasing silica and aluminium ions. These ions then combine to form stable silicate compounds, effectively trapping the nitrogen oxides in a solid form. The scientists were thrilled to observe that the harmful gases were permanently immobilized within the rock structure.

Which one of the following statements best reflects the most logical, rational, and practical suggestion implied by the passage?

A. This method can be used to produce silica and aluminium for industrial purposes at a large scale.

B. This process can be employed as a technique for mitigating air pollution by capturing and storing nitrogen oxides.

C. Sandstone formations can be turned into a valuable source of silica and aluminium through this method.

D. Mixing nitrogen oxides and water can create a powerful acid for industrial cleaning applications.

Explanation:

The last line of the paragraph depicts that the purpose of conducting this entire chemistry-based process was to test if the harmful nitrous oxides can be removed from the air or not. The paragraph is not based on industrial and large-scale production of silica and aluminium, but on the problem of mitigating air pollution. Also, the paragraph is not focused on the treatment of the sandstone, but on the problem of air pollution and removing the nitrous oxides from the air. Hence, the correct inference is option (B).

Therefore, B is the correct answer.

QUESTION #2

If 7@9@10 = 8 , 9@11@30 = 5 , 11@17@21 = 13, what is the value of 23@4@15?

A. 6

B. 8

C. 13

D. 15

Explanation:

This is a PYQ from 2023. The logic in the above question is as follows: 7@9@10 = 7+9+10 = 26 → 2 + 6 = 8

So, we first have to find out the sum of all the numbers and then add the digits of the sum at the end.

Applying the same logic to 23@4@15 we get 23 + 4 + 15 = 42 →4+2 = 6

Therefore, A is the correct answer.

QUESTION #3

The calendar for the year 2026 is same for

A. 2029

B. 2031

C. 2037

D. 2039

Explanation:

There is a shortcut to find out the calendar repetition. Whenever you are given a year that is 2 years after the leap year (2026 comes 2 years after the leap year 2024) we simply add 11 to it to find the year that will have the exactly same calendar.

Adding 11 to 2026 we get 2037. So, 2037 will have the same calendar as that of the year 2026.

Therefore, C is the correct answer.

QUESTION #4

If the price of an article is decreased by 20% and then the new price is increased by 25%, then what is the net change in the price?

A. 0%

B. 5% increase

C. 5% decrease

D. Cannot be determined due to insufficient data

Explanation:

Let us assume the initial price of an article is Rupees 100. As per the condition of the question, if the cost of the article is decreased by 20%, then the new price becomes:

New Price=100-20% of 100
New Price=100-20=Rs. 80

At this point, the price is Rupees 80. As per the condition of the question, the price is now increased by 25%.

New Price=80+25% of 80
New Price=80+20=Rs. 100

So, the initial price was Rupees 100 and the final price after all the changes is also Rupees 100 hence, the net change is 0%.

Therefore, A is the correct answer.

QUESTION #5

The sum of three consecutive integers is equal to their product. How many such possibilities are there?

A. Only one

B. Only two

C. Only three

D. No such possibility is there

Explanation:

Whenever an aspirant encounters such a question, its is important to catch and understand all the important keywords. Some of the important keywords used in the above question are:

1. Consecutive – all the numbers we will use in the above question should have a difference of 1.

2. Integers – The successive numbers can be negative or positive or may include 0.

The important condition here is the sum and the product of the numbers should be the same.

We can identify three such pairs and they are:

1. -3, -2, -1

2. -1, 0, 1

3. 1, 2, 3

For all the three pairs given above, the sum and the product of the numbers is the same.

Therefore, C is the correct answer.

(About our Expert: Mudit Gupta has been a mentor and faculty for the UPSC Civil Services exam for 8 years with expertise in CSAT, Polity, International Relations, and Current Affairs. He is known to break complex concepts into simpler ones that allow UPSC aspirants to develop a grip over the subject matter.)

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Manas Srivastava

Manas Srivastava is an Assistant Editor at The Indian Express Read More