JEE Main Pattern Practice Questions

Stop Reading. Start Scoring.

Sections 1 to 7 taught you the chapter. This section finds out whether you can use it under a clock, which is a completely different skill. There is no new theory here — just 30 questions built to the JEE Main pattern, and a marking scheme that punishes the thing students do most: guessing.

The rules of engagement

Key Point: Do not treat this as a reading exercise. Sit down with a blank sheet, a pen and a timer, and attempt all 30 questions in one unbroken sitting before you look at a single explanation.

The setup	What it is
Number of questions	30
Marking scheme	$+4$ correct, $-1$ incorrect, $0$ unattempted
Maximum score	$30 \times 4 = 120$ marks
Minimum possible score	$30 \times (-1) = -30$ marks
Suggested time limit	35 minutes (JEE Main pace is about 1 minute per question)
Allowed	rough sheet, your own brain
Not allowed	calculator, formula sheet, looking back at Sections 1 to 7

[Exam Tip] That $-1$ is not decoration. In the real paper, four wild guesses that produce one lucky hit earn you $4 - 3 = +1$ mark for four minutes of work — a terrible trade. But a question you have narrowed down to two options is worth attempting: on average that gives $\frac{4 - 1}{2} = +1.5$ marks per attempt. Narrow first, then commit. Leave blank only what you cannot narrow at all.

What this set covers

Topic	Questions	How many
SI units, prefixes and practical units	Q1 to Q3	3
Significant figures, arithmetic and rounding	Q4 to Q7	4
Dimensional formulae (mechanical, electrical, thermal)	Q8 to Q14	7
Dimensional consistency and unknown exponents	Q15 to Q19	5
Unit conversion between systems, $n_1 u_1 = n_2 u_2$	Q20 to Q22	3
Percentage error and error propagation	Q23 to Q27	5
Vernier callipers and screw gauge	Q28 to Q30	3

That spread is deliberate — it mirrors how JEE Main actually samples this chapter. Dimensions and errors together account for 12 of the 30 questions, because in the real paper they account for most of what gets asked from Units and Measurement. The difficulty mix is roughly 20% easy, 50% medium and 30% hard, so do not panic if a few feel brutal; they are meant to.

Scoring Yourself Honestly

Mark your sheet with the real scheme — $+4$, $-1$, $0$ — and total it. Do not award yourself half marks for "I knew that one really". The number you get is the number that matters.

The bands

Your score (out of 120)	Verdict	What to do next
96 to 120	Exam ready. You are at 80% or above on a hard set.	Move on. Chapter 1 will not cost you marks. Revisit only the specific questions you missed.
72 to 95	Solid, but leaking marks.	These are almost always slips, not gaps — a dropped power of ten, a forgotten factor of 2 in an error formula. Redo every wrong question without looking at the explanation first.
44 to 71	Shaky. The ideas are there; the execution is not.	For each wrong answer, go back to the section it came from (use the topic map above) and re-work its solved examples before re-attempting.
Below 44	Start again.	Work through Sections 1 to 7 properly, then Section 6's solved examples, then come back. Re-attempting this set now teaches you nothing.

Read your own answer sheet

Before you touch the explanations, sort your mistakes into three piles. This is the most valuable ten minutes in the whole section.

1. Concept errors — you did not know the dimensional formula, or the rule. Fixable by revision, and quickly.
2. Execution errors — right method, wrong arithmetic, or you rounded before the end. Fixable by slowing down for four seconds at the last step.
3. Reading errors — you found $\Delta Z / Z$ when the question asked for the percentage error, or gave the least count when it asked for the reading. These are the cheapest marks in the paper to win back, and the ones students refuse to take seriously.

Key Point: A student who scores 76 with three concept errors is in far better shape than one who scores 76 with nine reading errors. The first has three things to learn. The second has a habit to break, and habits take longer.

[Exam Tip] Every explanation below is written as a full step-by-step solution, so this set doubles as revision material. Read the explanation even for the questions you got right — sometimes you got there the slow way, and the fast way is what you will need in the exam hall.