NEET PhysicsUpdated 19 Oct 2026

Units and Measurement: NEET PYQs and weightage

Units and Measurement carries 3.2 of 100 Physics marks in NEET by past-paper share: 24 of the 758 tagged NEET Physics PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 14 of 30 Physics chapters.

Take the 25-question Units and Measurement test Formula sheet ↓All NEET Physics chapters

3.2/100 Weight in Physics

Exam importance (3/5, by past-paper share)

24 NEET PYQs

234 Practice questions

229 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Physics PYQs in the bank (24 of 758), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Units and Measurement: formula sheet for NEET

14 formulas, each with when to use it. Copy it onto one page of your notebook: that page is this chapter's handbook.

Principle of homogeneity
$[LHS] = [each term on RHS]$
$x = x_{0} + v_{0} t + \frac{1}{2} a t^{2} (every term is [L])$
Use it when: checking a formula, or finding the dimensions of an unknown constant in an added term
Force
$[F] = [M L T^{- 2}] (F = ma)$
Use it when: building the dimensions of pressure, work, momentum or any other mechanics quantity
Energy / work
$[E] = [M L^{2} T^{- 2}]$
$1 J = 1 kg m^{2} s^{- 2}$
Use it when: checking $\frac{1}{2} m v^{2}$ , $m g h$ or any expression claimed to be an energy
Speed, acceleration, density
$[v] = [M^{0} L T^{- 1}]$
$[a] = [M^{0} L T^{- 2}]$
$[ρ] = [M L^{- 3} T^{0}]$
Use it when: these are the building blocks for most dimension questions
Changing units
$n_{2} = n_{1} α^{- a} β^{- b} γ^{- c} (quantity [M^{a} L^{b} T^{c}], new units α kg, β m, γ s)$
Use it when: converting a value into a new unit system ( $1 cal = 4.2 J$ becomes $4.2 α^{- 1} β^{- 2} γ^{2}$ )
Deducing a relation
$T = k l^{x} g^{y} m^{z} \Rightarrow x = \frac{1}{2}, y = - \frac{1}{2}, z = 0$
$T = k \frac{l}{g} (the actual value is k = 2 π)$
Use it when: a quantity depends on up to three variables as a product; the constant $k$ never comes out of dimensions
Special functions
$sin θ$
$lo g x$
$e^{x} (arguments must be dimensionless)$
Use it when: a formula like $sin (ω t)$ or $e^{- k t}$ asks for the dimensions of $ω$ or $k$
Angles
$d θ = \frac{d s}{r} (rad)$
$d Ω = \frac{d A}{r ^{2}} (sr) (both dimensionless)$
Use it when: asked about supplementary units or the dimensions of an angle
Counting significant figures
Every non-zero digit counts; zeros between non-zero digits count; leading zeros ( $0.00 \dots$ ) never count; trailing zeros count only if there is a decimal point.
Use it when: counting digits, e.g. $0.06900$ has 4, $123000$ has 3, and $4.700 \times 1 0^{3}$ has 4
Multiply / divide
The answer keeps as many sig figs as the input with the fewest sig figs.
Use it when: computing products and quotients, e.g. $4.237 g \div 2.51 cm^{3} = 1.69 g cm^{- 3}$
Add / subtract
The answer keeps as many decimal places as the input with the fewest decimal places.
Use it when: computing sums and differences, e.g. $436.32 + 227.2 + 0.301 = 663.8 g$ (not $664 g$ )
Rounding off
If the dropped digit is more than 5, raise the digit before it; if less than 5, leave it; if exactly 5, raise only when the preceding digit is odd.
Use it when: rounding, e.g. $2.745$ becomes $2.74$ and $2.735$ becomes $2.74$
Relative error
$\frac{Δ a}{a} \times 100 %$
Use it when: comparing precision, e.g. $\pm 0.01$ on $1.02 g$ is about $1 %$ , but on $9.89 g$ it is about $0.1 %$
Error in a product
$Z = l b \Rightarrow \frac{Δ Z}{Z} = \frac{Δ l}{l} + \frac{Δ b}{b}$
Use it when: finding the error in an area or a product, e.g. $0.6 % + 1 % = 1.6 %$

Trap

A formula with the right dimensions can still be wrong. Dimensions cannot tell ½mv² from (3/16)mv², and they never give you constants like 2π. A formula with the wrong dimensions, however, is definitely wrong.

How does NEET ask Units and Measurement?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1PhysicsNEET UG PYQIntroduction of Units and Measurement

Try right here · No sign-in

The speed of light in vacuum is taken as unity. If light takes 6 min 40 s to reach the Earth from the Sun, the distance between the Sun and the Earth in new unit is:

Answer key (C) & worked solution

Correct answer: Option C

Time,

t = 6 min 40 s

= 360 + 40 = 400 s

Distance in new system

d = v t

= 1 \times 400 = 400

Q2PhysicsNEET UG PYQDimensions

A force defined by

F = α t^{2} + β t

acts on a particle at a given time t. The factor which is dimensionless. If

α

and

β

are constants, is:

\frac{α t}{β}

α β t

\frac{α β}{t}

\frac{β t}{α}

Answer key (A) & worked solution

Correct answer: Option A

F = α t^{2} = β t

[M^{1} L^{1} T^{2}] = [α] [T^{2}] = [β] [T]

So,

\frac{α T ^{2}}{β T}

is dimensionless So,

\frac{α T}{β}

Q3PhysicsNEET UG PYQDimensions

Math List - I with List – II Choose the correct answer from the options given below: List – IList – II(a)Gravitational constant (G)(i) [L

^{2}

^{- 2}

](b)Gravitational potential energy(ii)[M

^{- 1}

^{3}

^{- 2}

](c)Gravitational potential(iii)[LT

^{- 2}

](d)Gravitational intensity(iv)[ML

^{2}

^{- 2}

]

A(a) - (ii), (b) - (i), (c)-(iv), (d) - (iii)

B(a) - (ii), (b) - (iv), (c)-(i), (d) - (iii)

C(a) - (ii), (b) - (iv), (c)-(iii), (d) - (i)

D(a) - (iv), (b) - (ii), (c)-(i), (d) - (iii)

Answer key (B) & worked solution

Correct answer: Option B

(a) Gravitational constant ➝ (ii) [M

^{- 1}

^{3}

^{- 2}

] (b) Gravitational Potential energy ➝ (iv) [ML

^{2}

^{- 2}

] (c) Gravitational potential ➝ (i) [L

^{2}

^{- 2}

] (d) Gravitational intensity ➝ (iii) [LT

^{- 2}

]

Q4PhysicsNEET UG PYQDimensions

Planck's constant (h), speed of light in vacuum (c) and Newton's gravitational constant (G) are three fundamental constants. Which of the following combinations of these has the dimension of length?

\frac{h G}{c ^{5} /2}

\frac{h c}{G}

\frac{G c}{h ^{3/2}}

\frac{h G}{c ^{3/2}}

Answer key (D) & worked solution

Correct answer: Option D

ℓ \propto h^{x} G^{y} c^{z}

M^{0} L^{1} T^{0} = (M L^{2} T^{- 1})^{x} (M^{- 1} L^{3} T^{- 2})^{y} (L T^{- 1})^{z}

= M^{x - y} L^{2 x + 3 y + z} T^{- x - 2 y - z}

Equating: $\left. \begin{gathered} x - y = 0 \\ 2x + 3y + z = 1 \\ - x - 2y - z = 0 \\ \end{gathered} \right\}\begin{array}{*{20}{c}} { \Rightarrow x = \frac{1}{2};\,y = \frac{1}{2};\,z = - \frac{3}{2}} \\ { \Rightarrow \ell \propto \frac{{\sqrt {hG} }}{{{c^{\frac{3}{2}}}}}} \end{array}$

Q5PhysicsNEET UG PYQDimensions

If energy (E), velocity (V) and time (T) are chosen as the fundamental quantities, the dimensional formula of surface tension will be:

A[E – 2 V − 1 T − 3]

B[E V − 2 T − 1]

C[E V − 1 T − 2]

D[E V − 2 T − 2]

Answer key (D) & worked solution

Correct answer: Option D

[Surface Tension] = MT

^{- 2}

∴ MT − 2 = k E

^{a}

^{b}

^{c}

= k (ML

^{2}

T− -2)

^{a}

(LT − 1)

^{b}

^{c}

MT −2 = KM

^{a}

L2a + b T − 2a − b + c ∴ a = 1 2a + b = 0 - 2a - b + c = –2 On solving a = 1, b = -2, c = -2 ∴ Required answer is EV − 2 T − 2

Q6PhysicsNEET UG PYQAccuracy, Precision of Instruments and Errors in Measurement

A metal wire has mass

(0.4 \pm 0.002) g

, radius

(0.3 \pm 0.001) mm

and length

(5 \pm 0.02) c m

. The maximum possible percentage error in the measurement of density will nearly be:

A1.3%

B1.6%

C1.4%

D1.2%

Answer key (B) & worked solution

Correct answer: Option B

ρ = \frac{M}{V}

ρ = \frac{M}{π r ^{2} l}

\frac{Δ ρ}{ρ} = \frac{Δ M}{M} + \frac{2Δ r}{r} + \frac{Δ l}{l}

\frac{Δ ρ}{ρ} % = [\frac{0.002}{0.4} + \frac{2 ( 0.001 )}{( 0.3 )} + \frac{0.02}{5}] \times 100%

$\begin{gathered} = \frac{1}{2}\% + \frac{2}{3}\% + \frac{2}{5}\% \\ = 1.6\% \\ \end{gathered} $

Q7PhysicsNEET UG PYQThe International System of Units

A screw gauge has least count of 0.01 mm and there are 50 divisions in its circular scale. The pitch of the screw gauge is :

A0.5 mm

B1.0 mm

C0.01 mm

D0.25 mm

Answer key (A) & worked solution

Correct answer: Option A

Least count = \frac{Pitch}{no . of division on circular scale}

\Rightarrow 0.01 = \frac{p i t c h}{50}

pitch

= 0.01 \times 50 = 0.5 mm

Q8PhysicsNEET UG PYQSignificant figures and Rounding off

Each side of a metallic cube of mass 5.580 kg is measured to the 9.0 cm . Keeping the significant figures in view, the density of the material of the cube can be best expressed as

X \times 1 0^{3} kg m^{- 3}

where the value of

X

is:

A7.654

B7.7

C7.65

D7.6

Answer key (B) & worked solution

Correct answer: Option B

Density

== \frac{Mass}{Volume}

= \frac{5.580 kg}{( 9.0 cm ) ^{3}}

= \frac{5.580}{729} \times 1 0^{6} \frac{kg}{m ^{3}}

= 0.007654321 \times 1 0^{6} \frac{kg}{m ^{3}}

= 7.654 \times 1 0^{3} \frac{kg}{m ^{3}}

= 7.7 \times 1 0^{3} \frac{kg}{m ^{3}}

Hence, on comparing

X = 7.7

Which topics in Units and Measurement carry the most questions?

All 6 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Dimensions	12	107
Accuracy, Precision of Instruments and Errors in Measurement	6	70
Significant figures and Rounding off	3	32
The International System of Units	2	10
Introduction of Units and Measurement	1	13
Miscellaneous Examples	0	2

Why does Units and Measurement show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Units and Measurement, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

How ViJEEta scores you

What happens when you test Units and Measurement?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

Start the Units and Measurement test

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Units and Measurement: NEET PYQs and weightage

Units and Measurement: formula sheet for NEET

Principle of homogeneity

Force

Energy / work

Speed, acceleration, density

Changing units

Deducing a relation

Special functions

Angles

Counting significant figures

Multiply / divide

Add / subtract

Rounding off

Relative error

Error in a product

How does NEET ask Units and Measurement?

Which topics in Units and Measurement carry the most questions?

Why does Units and Measurement show "–" until you answer 3 questions?

What happens when you test Units and Measurement?

Chapters either side of Units and Measurement by weight