NEET ChemistryUpdated 19 Oct 2026

Practical Chemistry: NEET PYQs and weightage

Practical Chemistry carries 2.5 of 100 Chemistry marks in NEET by past-paper share: 18 of the 707 tagged NEET Chemistry PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 22 of 26 Chemistry chapters.

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2.5/100 Weight in Chemistry

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

18 NEET PYQs

249 Practice questions

185 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Chemistry PYQs in the bank (18 of 707), 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.

Practical Chemistry: 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.

Kjeldahl nitrogen
$% N = \frac{1.4 \times N _{1} \times ( V - v )}{w}$
Use it when: $N H_{3}$ from $w$ g of compound is absorbed in $V$ mL of acid of normality $N_{1}$ , and $v$ mL of that acid is left unused (find $v$ by back-titration: $N_{acid} \times v = N_{alkali} \times V_{alkali}$ ). Not valid for nitro, azo ( $- N = N -$ ) or ring nitrogen (pyridine).
Dumas, N2 volume at STP
$V_{0} = \frac{( P - a ) \times V \times 273}{760 \times ( 273 + t )}$
Use it when: $N_{2}$ is collected moist at $t^{\circ} C$ and $P$ mm Hg, where $a$ is the aqueous tension at $t^{\circ} C$ .
Dumas nitrogen
$% N = \frac{28 \times V _{0} \times 100}{22400 \times w}$
Use it when: you have $V_{0}$ in mL at STP from $w$ g of compound.
Liebig carbon
$% C = \frac{12}{44} \times \frac{mass of C O _{2}}{w} \times 100$
Use it when: the gain in mass of the potash ( $KOH$ ) tubes gives the mass of $C O_{2}$ .
Liebig hydrogen
$% H = \frac{2}{18} \times \frac{mass of H _{2} O}{w} \times 100$
Use it when: the gain in mass of the $CaC l_{2}$ tube gives the mass of $H_{2} O$ .
Carius halogen
$% X = \frac{X \times a \times 100}{( 108 + X ) \times w}$
Use it when: $a$ g of $AgX$ is formed. Use $X = 35.5$ ( $AgCl$ 143.5), $80$ ( $AgBr$ 188) or $127$ ( $AgI$ 235).
Carius sulphur
$% S = \frac{32 \times a \times 100}{233 \times w}$
Use it when: $a$ g of $BaS O_{4}$ is formed from $w$ g of compound.
Phosphorus as ammonium phosphomolybdate
$% P = \frac{31 \times m _{1} \times 100}{1877 \times m}$
Use it when: $m_{1}$ g of $(N H_{4})_{3} P O_{4} \cdot 12Mo O_{3}$ is formed from $m$ g of compound.
Phosphorus as Mg2P2O7
$% P = \frac{62 \times m _{1} \times 100}{222 \times m}$
Use it when: P is precipitated with magnesia mixture and ignited to $m_{1}$ g of $M g_{2} P_{2} O_{7}$ .
Oxygen by difference
$% O = 100 - (sum of % of all other elements)$
Use it when: the question gives C, H, N and so on but not O.
Molecular formula
$M = 2 \times vapour density$
$n = \frac{M}{empirical formula mass}$
Use it when: you have found the empirical formula from the percentages and need to scale it up.
Zeisel method
$moles of AgI = moles of - OC H_{3} groups$
Use it when: you need to count the methoxy groups. Divide the moles of $AgI$ by the moles of compound.
Retardation factor
$R_{f} = \frac{distance moved by substance from baseline}{distance moved by solvent from baseline}$
Use it when: you are reading a TLC plate or paper chromatogram. $R_{f}$ can never exceed $1$ .
Steam distillation
$p_{atm} = p_{1} (organic) + p_{2} (water)$
Use it when: you have a water-immiscible, steam-volatile liquid such as aniline. The mixture boils just below $373 K$ .

Trap

In Dumas, students put the barometer reading P straight into the gas equation. The N₂ is collected moist, so first subtract the aqueous tension and use (P − a).

How does NEET ask Practical Chemistry?

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.

Q1ChemistryNEET UG PYQPurification Techniques

Try right here · No sign-in

Paper chromatography is an example of :

Answer key (D) & worked solution

Correct answer: Option D

It is an example of partition chromatography as mixture of substance are separated by partition.

Q2ChemistryNEET UG PYQQualitative Analysis of Elements

Which one of the following reactions does NOT belong to “Lassaigne’s test”?

Na + X Δ NaX

2CuO + C Δ 2Cu + C O_{2}

Na + C + N Δ NaCN

2Na + S Δ N a_{2} S

Answer key (B) & worked solution

Correct answer: Option B

2CuO + C Δ 2Cu + C O_{2}

Q3ChemistryNEET UG PYQQualitative Analysis of Elements

During Lassaigne's test, the elements present in an organic compound are converted from :

ACovalent form to covalent form

BIonic form to ionic form

CCovalent form to ionic form

Dlonic form to covalent form

Answer key (C) & worked solution

Correct answer: Option C

During Lassaigne's test, the element present in an organic compound are converted from covalent form to ionic form.

Q4ChemistryNEET UG PYQPurification Techniques

On heating, some solid substances changes from solid to vapour state without passing through liquid state. The technique used for the purification of such substances based on the above principle is known as

ASublimation

BDistillation

CChromatography

DCrystallization

Answer key (A) & worked solution

Correct answer: Option A

Sublimation is a purification technique used for solid substance that are convert into vapour state directly without going through liquid state.

Q5ChemistryNEET UG PYQDetection of Functional Groups and preparation of double salts

During the preparation of Mohr’s salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of Fe

^{2 +}

ion?

AConcentrated sulphuric acid

BDilute nitric acid

Cdilute sulphuric acid

Ddilute hydrochloric acid

Answer key (C) & worked solution

Correct answer: Option C

Cationic hydrolysis takes place during crystallization of mohrs salt, which needs to be avoided. Cationic hydrolysis, leads to acidic solution, so dilute acid is added to suppress hydrolysis. In order to avoid contamination, same anion acid is used.

Q6ChemistryNEET UG PYQQuantitative Analysis of Elements

In the Kjeldahl’s method for estimation of Nitrogen present in a soil sample, Ammonia evolved from 0.75 g of sample neutralized 10 ml of 1M H

_{2}

_{4}

. The percentage of Nitrogen in the soil is

A35.33

B43.33

C37.33

D45.33

Answer key (C) & worked solution

Correct answer: Option C

_{e q t s}

.of H

_{2}

_{4}

= 1 × 2 × 10 = 20 ⇒ m

_{e q t s}

. of NH

_{3}

used = 20

\frac{w}{17} = 20 \times 1 0^{- 3}

w = 0.34 g Mass of nitrogen = 0.28 g

% = \frac{0.28}{0.75} \times 100 = 37.33%

Q7ChemistryNEET UG PYQDetection of Functional Groups and preparation of double salts

In potash alum, the ratio of

K^{+}

and

SO_{4}^{2 -}

ions is

2 : 1

2 : 3

3 : 2

1 : 2

Answer key (D) & worked solution

Correct answer: Option D

Potash alum

K_{2} SO_{4} \cdot Al_{2} (SO_{4})_{3} \cdot 24 H_{2} O

No. of

K^{+} = 2

No. of

SO_{4}^{2 -} = 4

Ratio

\frac{K ^{+}}{SO _{4}^{2 -}} = \frac{2}{4} = \frac{1}{2}

Q8ChemistryNEET UG PYQSalt Analysis-Cation

Match List I with List II List-I (Ion)List-II (Group Number in Cation Analysis)A. Co

^{2 +}

I. Group-IB. Mg

^{2 +}

I. Group-IIIC. Pb

^{2 +}

I. Group-IVD. Al

^{3 +}

I. Group-VI Choose the correct answer from the options given below.

AA-III, B-II, C-IV, D-I

BA-III, B-II, C-I, D-IV

CA-III, B-IV, C-II, D-I

DA-III, B-IV, C-I, D-II

Answer key (D) & worked solution

Correct answer: Option D

A-III, B-IV, C-I, D-II

Which topics in Practical Chemistry carry the most questions?

All 7 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Quantitative Analysis of Elements	4	56
Qualitative Analysis of Elements	4	52
Purification Techniques	4	44
Detection of Functional Groups and preparation of double salts	3	11
Salt Analysis-Cation	2	52
Salt Analysis-Anion	1	26
Miscellaneous Examples	0	8

Why does Practical Chemistry show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Practical Chemistry, 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 Practical Chemistry?

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 Practical Chemistry test

Chapters either side of Practical Chemistry by weight

Redox Reactions Weight 2.7/100 p-Block Elements (Group 13 and 14) Weight 2.7/100 Haloalkanes and Haloarenes Weight 2.4/100 Gasesous State* Weight 2.1/100

Practical Chemistry: NEET PYQs and weightage

Practical Chemistry: formula sheet for NEET

Kjeldahl nitrogen

Dumas, N2 volume at STP

Dumas nitrogen

Liebig carbon

Liebig hydrogen

Carius halogen

Carius sulphur

Phosphorus as ammonium phosphomolybdate

Phosphorus as Mg2P2O7

Oxygen by difference

Molecular formula

Zeisel method

Retardation factor

Steam distillation

How does NEET ask Practical Chemistry?

Which topics in Practical Chemistry carry the most questions?

Why does Practical Chemistry show "–" until you answer 3 questions?

What happens when you test Practical Chemistry?

Chapters either side of Practical Chemistry by weight