NEET Chemistry Chapter-wise Important Questions

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Chapter-Wise Important Questions for NEET Exam

Chapter 1: Some Basic Concepts of Chemistry

1. What will be the normality of a solution obtained by mixing 0.45N and 0.60N NaOH in the ratio of 2:1 by volume?

N = N₁V₁ + N₂V₂V₁ + V₂ = 0.5

Therefore, the normality of the mixed solution is 0.5N.

2. A measured temperature on the Fahrenheit scale is 200℉. What will be its value in ℃?

℉ = 95 ℃ + 32

200 = 95 ℃ + 32

Therefore, the temperature on the Celsius scale is 93.3℃.

Chapter 2: Structure of Atom

1. What is the total energy of the first orbit of an H-atom?

Energy = – 2³k²e⁴mh²

2. What is the electronic configuration of Fe³⁺?

Fe³⁺ (23 electrons) = [Ar] 3d⁵

Chapter 3: Classification of Elements and Periodicity in Properties

1. What are Eka-aluminium and Eka-silicon?

Eka-aluminium is Gallium and Eka-silicon is Germanium.

2. What elements from atomic numbers 58-71 are known?

They are called Lanthanide series elements.

Chapter 4: Chemical Bonding and Molecular Structure

1. What is the most favourable condition for forming ionic bonds?

Larger cation has lesser polarisation power, whereas smaller anion is less polarisable.

2. Write the hybridization and shape of N(SiH₃)₃.

The N-atom will donate its lone pair of electrons to the vacant d-orbital of Si. Therefore, it has sp² hybridisation and planar shape.

Chapter 5: States of Matter: Gases and Liquids

1. If the temperature of an ideal gas is sealed, the rigid container is increased to 1.5 times the initial value (in K). What happens to its density?

For a sealed rigid container, mass and volume remain the same. Hence, density will remain the same even if there is an increase in temperature.

2. At low pressure, what will be Vander Waals’ equation for CH₄?

Vander Waals’ equation is

(P + aV²) (V – b) = RT

At low P and high T, (V – b) = V

Therefore, Vander Waals’ equation for CH₄ will be PV = RT – aV .

Chapter 6: Thermodynamics

1. What is the specific heat at constant pressure per gram of gas when its molar mass is M?

Specific heat at constant pressure per gram, Cₚ = RM(-1).

2. When does the work done during the expansion of a gas depend on pressure?

During isothermal expansion

Work done = nRT logₑVfVi

During adiabatic expansion

Work done = P₁V₁ – P₂V₂-1

In both cases, work done depends on pressure.

Chapter 7: Equilibrium

1. Which concept can explain the acidity of BF₃?

According to the Lewis concept, a positive charge or an electron-deficient species act as Lewis acid. BF₃ is an electron-deficient compound, with B having only 6 electrons.

2. What is the correct order of vapour pressure of water, acetone, and ether at 30℃?

Greater the boiling point, the lesser the vapour pressure. Therefore, the correct order will be

Ether > Acetone > Water

Chapter 8: Redox Reactions

1.3.92 g/L of a sample of ferrous ammonium sulphate reacts completely with 50 mL N10 KMnO₄ solution. Calculate the percentage purity of the sample.

N₁V₁ = N₂V₂

N₁ x 1000 = 110 x 50

N₁ = 1200 

Equivalent weight of ferrous ammonium sulphate = molar weight = 392

Strength of pure salt = 392 x 1200  = 1.96 g/L

% purity = 1.963.92 x 100 = 50%

Therefore, the percentage purity of the sample is 50%.

2. Calculate the oxidation state of V in Rb₄Na[HV₁₀O₂₈].

4 (+1) + (+1) + (+1) + 10x + 28 (-2) = 0

x = +5

Therefore, the oxidation state of V is +5.

Chapter 9: Hydrogen

1. What is semi-water gas?

The mixture of CO, H₂, and N₂ is known as semi-water gas.

2. Ordinary water is not used as a moderator in nuclear reactors. Why?

Ordinary water absorbs too many neutrons to be used with unenriched natural uranium. Therefore, it affects the operation of such reactors and increases the overall cost.

Chapter 10: s-block Elements

1. Arrange the following ions in the increasing order of their ‘Hydration Energy.’

Be²⁺, Mg²⁺, Ca²⁺, Ba²⁺, Si²⁺

Smaller the size of the cation, the higher the hydration energy. Therefore, the correct order is

Ba²⁺ < Si²⁺ < Ca²⁺ < Mg²⁺ < Be²⁺

2. KO₂ is used in oxygen cylinders in space and submarines. Why?

2KO₂ + 2H₂O → 2KOH + H₂O₂ + O₂

KO₂ is used as an oxidising agent. In space capsules, it is used as an air purifier. In submarines, it is used in breathing masks. These are all because it produces oxygen and removes carbon dioxide.

Chapter 11: Organic Chemistry – Some Basic Principles and Techniques

1. How many isomers of glucose are possible?

Glucose has four dissimilar asymmetric carbon atoms. Hence, number of isomers = 24 = 16.

2. What is the cause of resonance in a molecule?

Resonance in a molecule arises due to the delocalisation of -electrons.

Chapter 12: Hydrocarbons

1. What is the correct decreasing order of reactivity of alkenes towards given hydrogen halides propene, butene, and pentene?

The reactivity of alkenes is inversely proportional to the number of carbon atoms. Therefore, the correct decreasing order is

Propene > Butene > Pentene.

2. 2-methyl propene is isomeric with but-1-ene. How can you distinguish them?

Ozonolysis of these will give different products which can differentiate between but-1-ene and 2-methyl propene.

Chapter 13: Environmental Chemistry

1. What is the BOD value of clean water?

BOD value is the amount of oxygen needed to decompose the organic material present in the water. For pure or clean water is 5ppm.

2. What are secondary pollutants?

Secondary pollutants are not emitted directly from any source. They form by reacting with the molecules present in the atmosphere. Some secondary pollutants are nitric acid, PAN, etc.

Chapter 14: Solid State

1. At what angles for the first-order diffraction, spacing between two planes are and 2, respectively?

n = 2d sin

In first case, n = 1, d =

1 x = 2d sin

sin = 12 = sin 30°

= 30°

In second case, n = 1, d = 2

1 x   = 2 x 2 x sin

sin = 1 = sin 90°

= 90°

Therefore, the angles are 30° and 90°.

2. Which type of magnetic behaviour is shown by ‘magnetite’ (Fe3O4)?

In Fe3O₄, iron and oxygen atoms are present in +5 and -2 ionic states. They are arranged in oppositely aligned magnetic moments. Irrespective of this, at room temperature, Fe3O₄ shows ferromagnetism due to different values of magnetic moments of both atoms.

Chapter 15: Solutions

1. What is the mathematical expression for Raoult’s law?

According to Raoult’s law,

P⁰-PP⁰ = nn+N

After simplifying it, P⁰-PP⁰ = nN.

2. 18g of glucose (C6H12O6) is added to 178.2g of water. What will be the vapour pressure of water for this aqueous solution at 100℃?

Moles of glucose = 18180 = 0.1

Moles of water = 178.218 = 9.9

Total mass = 0.1 + 9.9 = 10

H₂O = Mole fraction x Total pressure = 9.910 x 760 = 752.40

Therefore, the vapour pressure of water for this aqueous solution at 100℃ is 752.40 Torr.

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Chapter 16: Electrochemistry

1. Standard free energies of formation (in kJ/mol) at 298 K are = -237.2, -394.4, and -8.2  for H₂O (l), CO₂ (g), and pentane (g), respectively. What will be the value of Ecell⁰ for the pentane-oxygen fuel cell?

The balanced equation for pentane-oxygen cell reaction will be

C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O; n=32

r G⁰= [5 x f G⁰(CO₂) + 6 x f G⁰(6H₂O)] – [f G⁰(C₅H₁₂) + 8 x f G⁰(O₂)]

r G⁰= [5 x (-394.5) + 6 x (-237.2)] – [(-8.2) + 0] = -3387 kJ/mol

f G⁰= -nFEcell⁰

-3387000 = -32 x 96500 x Ecell⁰

Ecell⁰ = 1.0968 V

Therefore, Ecell⁰ for the pentane-oxygen fuel cell is 1.0968 V.

2. What would be the product of electrolysis of molten ICl₃ is electrolysed?

In the molten state, ICl₃ ionises as follows

2ICl₃ → ICl2+ + ICl4–

Therefore, both I₂ and Cl₂ are liberated at both electrodes.

Chapter 17: Chemical Kinetics

1. In the presence of a catalyst, what happens to the heat evolved or absorbed during the reaction?

There is no effect on the heat evolved or absorbed during the reaction in the presence of a catalyst. It is because the catalyst does not participate in the reaction.

2. Name the factor on which the value of the rate constant of the pseudo-first-order reaction depends.

The value of the rate constant of the pseudo-first-order reaction depends on the concentration of reactants present in excess.

Chapter 18: Surface Chemistry

1. Which colligative property is used to determine the molar mass of a polymer?

For the molar mass of a polymer, osmotic pressure is preferred because it is done at normal temperature. At higher temperatures, molecules are not stable.

2. What happens to Brownian motion when the particle size of the dispersed phase increases in colloidal solution?

Brownian movement is due to unequal bombardments of moving molecules of dispersion medium on colloidal particles. The bigger size of particles reduces the movement.

Chapter 19: General Principles and Processes of Isolation of Elements

1. What is the formula of Feldspar?

Feldspar is K2O.Al2O3.6SiO2.

2. You are given a mixture of ZnS and PbS. How will you separate them?

The froth flotation process can separate the two compounds by adding NaCN. It is because ZnS forms soluble complexes while PbS forms forth.

Chapter 20: p-Block Elements

1. Arrange the boiling points of group 16 hydrides in increasing order.

The boiling point depends upon the intermolecular forces of attraction. But, due to H-bonding in H2O molecules, its boiling point gets higher compared to others. Therefore, the correct order is

H2S < H2Se < H2Te < H2O

2. What is the correct order of Cl-O bond lengths in ClO⁻, ClO₂⁻, ClO₃⁻, and ClO₄⁻?

The bond length of compounds is inversely proportional to bond order. Also, the greater the delocalisation of -electrons, the shorter the bond length. Therefore, the correct order is

ClO₄⁻ < ClO₃⁻ < ClO₂⁻ < ClO⁻

Chapter 21: d- and f-Block Elements

1. How many total rare earth elements are there?

Lanthanides are known as rare earth elements. Therefore, there are a total of 14 rare earth elements.

2. Arrange the decreasing order of the magnitude of the ionic radii of La3+, Ce3+, Yb3+, and Pm3+?

Due to lanthanide contraction, ionic radii decrease. Hence, the order will be

La3+ > Ce3+ > Pm3+ > Yb3+

Chapter 22: Coordination Compounds

1. Give the IUPAC name of K3[Al(C2O4)3].

IUPAC name of K3[Al(C2O4)3] is potassium trioxalatoaluminate(III).

2. Calculate the coordination number of Co in [Co(NH3)6]2+.

The coordination number equals the total number of ligands in the compound. Hence, the coordination number of Co is 6.

Chapter 23: Haloalkanes and Haloarenes

1. An organic compound ‘X’ on treatment with Pyridinium Chlorochromate (PCC) in CH2Cl2 gives compound ‘Y.’ Compound ‘Y’ reacts with I2/NaOH to form iodoform. Name the compound ‘X.’

Compound ‘X’ will be CH3CH2OH.

2. What will be the product of hydrolysis of 2-Bromo-3-methyl butane?

It will be 2-methyl-2-butanol.

Chapter 24: Alcohols, Phenols, and Ethers

1. Write the correct order of acidic strength of the following compounds:

Phenol, p-Cresol, m-Nitrophenol, p-Nitrophenol

The acidity of a compound increases with the increase in electron-withdrawing groups and decreases with the increase in electron releasing groups. Hence, the order of acidic strength is

p-Nitrophenol > m-Nitrophenol > Phenol > p-Cresol

2. How will you distinguish between 1° and 2° alcohols?

1° and 2° alcohols can be distinguished by Lucas reagent and Victor-Meyer Test. Also, 2° alcohols can give a positive Iodoform test while 1° cannot.

Chapter 25: Aldehydes, Ketones, and Carboxylic Acids

1. Name the reagent that reacts with both aldehyde and acetone easily.

Grignard’s reagent has carbanion as a nucleophile that can attack even at the carboxyl group of the ketone.

2. Write the correct order of reactivity of PhCOPh, CH3CHO, and CH3COCh3 with PhMgBr.

The reactivity of carbonyl compounds with any nucleophile is based on the electrophilicity of carbonyl carbon and steric crowding around it. Hence, the correct order of reactivity is

CH3CHO > CH3COCH3 > PhCOPh

Chapter 26: Organic Compounds Containing Nitrogen

1. When a compound ‘X’ reacts with CHCl₃ in the presence of NaOH, a foul smell is formed. Name the reaction.

When a compound ‘X’ reacts with CHCl₃ in the presence of NaOH, a foul-smelling gas ‘isocyanide’  is formed. This gas, on further reduction, forms a secondary amine. It is a carbylamine reaction.

2. How many carbon-containing primary amines will form when four carbon-containing primary amines react with Br and NaOH?

When primary amines react with Br and NaOH, one carbon fewer results in animes being formed. It is a Hoffman-bromamide reaction. Therefore, this reaction will form three carbon-containing primary amines.

Chapter 27: Biomolecules

1. What is the principal role of PUFA?

The fatty acids that contain more than one double bond in their backbone are known as Polyunsaturated Fatty Acids (PUFA). It supplies essential fatty acids and enhances atherosclerosis and cholesterol levels in the body.

2. Name the elements Protistan shells and Sponge spicules made up of.

Protistan shells and Sponge spicules are made up of Silica and Calcium.

Chapter 28: Polymers

1. Name the polymer that can absorb over 90% of its mass of water and doesn’t stick to wounds.

Rayon.

2. Give the characteristics of thermosetting polymers.

They have heavily branched cross-linked polymers. And cannot reuse them.

Chapter 29: Chemistry in Everyday Life

1. What are Tranquillisers?

Tranquillisers are substances that affect the central nervous system and induce sleep.

2. When soap or detergent are added to the water, the surface tension of water is reduced by both. Why?

When soap or detergent is added to the water, the ionic part of soap or detergent attracts grease. And repel water molecules. As a result, the hydrogen bonds that hold the water molecules get weakened. Therefore, the surface tension of water decreases.

Also see: NEET Chemistry: Chapter-wise Weightage & Important Topics

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