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Science (English Medium) Class 12 - CBSE Important Questions for Chemistry

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What are interstitial compounds?

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Define lanthanoid contraction.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Lanthanoids

Account for the following :

Zr and Hf have almost similar atomic radii.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Lanthanoids

Complete the following equations : 2 MnO2 + 4 KOH + O2 →

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

Complete the following equations : 2 Na2CrO4 + 2 H + →​

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

`E_((M^(2+)/M)`

Cr Mn Fe Co Ni Cu
-0.91 -1.18 -0.44 -0.28 -0.25 -0.34

From the given data of E0 values, answer the following questions :

(1) Why is `E_(((Cu^(2+))/(Cu)))` value exceptionally positive

(2) Why is `E_(((Mn^(2+))/(Mn)))` value is highly negative as compared to other elements

(3) Which is the stronger reducing agents Cr2+ or Fe2+ ? Give Reason.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Why do actinoids show a wide range of oxidation states?

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Actinoids

Write on similarity between the chemistry of lanthanoids and actinoids.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Actinoids

Explain effects of lanthanoid contraction.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Lanthanoids

Write the formula of an oxo-anion of Manganese (Mn) in which it shows the oxidation state equal to its group number.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

Answer the following question.
When MnO2 is fused with KOH in the presence of KNO3 as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionates in an acidic solution to give a purple compound (B).  An alkaline solution of compound (B) oxidizes KI to compound (C) whereas an acidified solution of compound (B) oxidizes KI to (D). Identify (A), (B), (C), and (D).

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

Using IUPAC norms, write the formula of potassium trioxalatochromate(III).

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

Give reasons for the following statement:

Transition metals and most of their compounds show paramagnetic behaviour.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Give reason for the following statement:

Physical and chemical properties of the 4d and 5d series of the transition elements are quite similar to expected.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Define transition metals.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Electronic Configurations of the d-block Elements

How is the variability in oxidation states of transition metals different from that of p-block elements?

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Assertion (A) : Copper is a non-transition element.

Reason (R) : Copper has completely filled d-orbitals in its ground state.

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Electronic Configurations of the d-block Elements

Which of the following characteristics of transition metals is associated with their catalytic activity?

Appears in 2 question papers
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

When a coordination compound CoCl3.6NH3 is mixed with AgNO3, 3 moles of AgCl are precipitated per mole of the compound. Write the structural formula of the coordination compound.

Appears in 2 question papers
Chapter: [5] Coordination Compounds
Concept: Isomerism in Coordination Compounds >> Stereoisomerism

Draw the geometrical isomers of complex \[\ce{[Co(en)2Cl2]+}\].

Appears in 2 question papers
Chapter: [5] Coordination Compounds
Concept: Isomerism in Coordination Compounds >> Stereoisomerism
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