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Science (English Medium) Class 12 - CBSE Important Questions

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Actinoid elements show wide range of oxidation states.

Appears in 6 question papers
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Actinoids

Account for the following : Nitrogen does not form pentahalide.

Appears in 6 question papers
Chapter: [7] P - Block Elements
Concept: Group 15 Elements - The Nitrogen Family >> Dinitrogen

Draw the structure of the semicarbazone of ethanal.

Appears in 6 question papers
Chapter: [8] Aldehydes, Ketones and Carboxylic Acids
Concept: Chemical Reactions of Aldehydes and Ketones - Nucleophilic Addition Reactions

Why is the α-hydrogens of aldehydes and ketones are acidic in nature?

Appears in 6 question papers
Chapter: [8] Aldehydes, Ketones and Carboxylic Acids
Concept: Chemical Reactions of Aldehydes and Ketones - Reactions Due to α-hydrogen

Account for the following:

Although the amino group is o, p-directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.

Appears in 6 question papers
Chapter: [9] Amines
Concept: Chemical Reactions of Amines - Electrophilic Substitution

Give simple chemical tests to distinguish between the following pair of compounds:

Benzaldehyde and Benzoic acid

Appears in 6 question papers
Chapter: [9] Amines
Concept: Nomenclature of Amines

What is Hinsberg's reagent?

Appears in 6 question papers
Chapter: [9] Amines
Concept: Chemical Reactions of Amines - Reaction with Arylsulphonyl Chloride

Give reasons for the following:

Ammonolysis of alkyl halides is not a good method to prepare pure primary amines.

Appears in 6 question papers
Chapter: [9] Amines
Concept: Preparation of Amines

Evaluate: `int_0^π (x sin x)/(1 + cos^2x) dx`.

Appears in 6 question papers
Chapter: [7] Integrals
Concept: Methods of Integration>Integration Using Trigonometric Identities

Write S.I unit of electric flux.

Appears in 6 question papers
Chapter: [1] Electric Charges and Fields
Concept: Electric Flux

Define Electric Flux.

Appears in 6 question papers
Chapter: [1] Electric Charges and Fields
Concept: Electric Flux

Derive an expression for the mutual inductance of two long co-axial solenoids of same length wound one over the other,

Appears in 6 question papers
Chapter: [4] Moving Charges and Magnetism
Concept: Solenoid

Why is it necessary to introduce a cylindrical soft iron core inside the coil of a galvanometer?

Appears in 6 question papers
Chapter: [4] Moving Charges and Magnetism
Concept: Moving Coil Galvanometer

Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.

Appears in 6 question papers
Chapter: [8] Electromagnetic Waves
Concept: Electromagnetic Spectrum

Write two uses of the following radiation.

X-rays

Appears in 6 question papers
Chapter: [8] Electromagnetic Waves
Concept: Electromagnetic Spectrum

Write two important limitations of a refracting telescope over a reflecting-type telescope.

Appears in 6 question papers
Chapter: [9] Ray Optics and Optical Instruments
Concept: Optical Instruments >> Telescope

With the help of a diagram, show how a plane wave is reflected from a surface. Hence, verify the law of reflection.

Appears in 6 question papers
Chapter: [10] Wave Optics
Concept: Reflection of a Plane Wave by a Plane Surface

Define the term 'intensity of radiation' in terms of photon picture of light.

Appears in 6 question papers
Chapter: [11] Dual Nature of Radiation and Matter
Concept: Experimental Study of Photoelectric Effect

Write Einstein’s photoelectric equation?

Appears in 6 question papers
Chapter: [11] Dual Nature of Radiation and Matter
Concept: Einstein’s Photoelectric Equation: Energy Quantum of Radiation

Write two important limitations of Rutherford's nuclear model of the atom.

Appears in 6 question papers
Chapter: [12] Atoms
Concept: Alpha-particle Scattering and Rutherford’s Nuclear Model of Atom
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