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

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Complete the following chemical equations:

`(i) Cr_2O_7^(2-)+6Fe^(2+)+14H^+ ->`

`(ii) 2CrO_4^(2-)+2H^+ ->`

`(iii) 2MnO_4^-+5C_2O_4^(2-)+16H^+ ->`

 
 
 
Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Complete the following equations:

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

Complete the following equations: Cr2O72- + 14H+ + 6I →

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Write the element which shows maximum number of oxidation states. Give reason.

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Which element has the highest m.p?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Which element shows only +3 oxidation state?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Which element is a strong oxidising agent in +3 oxidation state and why?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Why do the transition elements have higher enthalpies of atomisation?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

In 3d series (Sc to Zn), which element has the lowest enthalpy of atomisation and why?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Complete the following equation:

\[\ce{2MnO4- + 6H+ + 5NO2- ->}\]

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

What are the consequences of lanthanoid contraction?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Lanthanoids

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

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Account for the following: 

Zn, Cd and Hg are soft metals.

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Lanthanoids

Following are the transition metal ions of 3d series:

Ti4+, V2+, Mn3+, Cr3+

(Atomic numbers: Ti = 22, V = 23, Mn = 25, Cr = 24)

Answer the following:

1) Which ion is most stable in an aqueous solution and why?

2) Which ion is a strong oxidising agent and why?

3) Which ion is colourless and why?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Complete the following equations:

`2MnO_4^(-)+16H^++5S^(2-)rarr`

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

How would you account for the following? 

Zr (Z = 40) and Hf (Z = 72) have almost identical radii.

 

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

Why do transition elements show variable oxidation states ? In 3d series (Sc to Zn), which elements shows the maximum number of oxidation state and why ?

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Physical Properties of the Transition Elements (d-block)

How would you account the following :

Highest fluoride of Mn is MnF4 whereas the highest oxide is Mn2O7.

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: F-block Elements >> The Actinoids

Complete the following equation :

\[3 {MnO}_4^{2 -} + 4 H^+ \to\]
Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements

Account for the following : 
Manganese shows maximum number of oxidation states in 3d series. 

Appears in 1 question paper
Chapter: [4] d-block and f-block Elements
Concept: Important Compounds of Transition Elements
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