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Science (English Medium) Class 12 - CBSE Important Questions

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 Write the structures of main products when benzene diazonium chloride (C6 H5 N+2CI)C6 H5 N2+CI- reacts with the :Cu/HBr

Appears in 1 question paper
Chapter: [7] Alcohols, Phenols and Ethers
Concept: Methods of Preparation of Phenols

Write the structures of A, B and C in the following reactions :

\[ C_6 H_5 {NO}_2 \to^{Sn/HCI} A \to^{{NaNO}_2 /HCI}_{273 K} B \to^{H_2 O}_∆ C\]

Appears in 1 question paper
Chapter: [7] Alcohols, Phenols and Ethers
Concept: Chemical Properties of Alcohols and Phenols

Write the structures of A, B and C in the following reactions :

\[{CH}_3 CI \to^{KCN} A \to^{LiAIH} B \to^{{HNO}_2}_{273K} C\]
Appears in 1 question paper
Chapter: [7] Alcohols, Phenols and Ethers
Concept: Methods of Preparation of Alcohols

Draw the structures of the following :

H2S2O7

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Compounds of Sulphur

Account for the following :

HClO4 is a stronger acid than HClO.

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 17 Elements - The Halogen Family >> Oxoacids of Halogens

The two O−O bond lengths in the ozone molecule are equal.

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Ozone

Account for the following :

H3PO2 is a stronger reducing agent than H3PO3.

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Oxoacids of Sulphur

 Complete and balance the following equations: 
S+H2SO4(conc.)  → 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Sulphuric Acid

Complete and balance the following equation: 

\[\ce{PCl3 + H2O ->}\] 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 15 Elements - The Nitrogen Family >> Phosphorus Halides

Write balanced chemical equations involved in the following reactions:
Chlorine gas reacts with cold and dilute NaOH 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Compounds of Halogens

Write balanced chemical equations involved in the following reactions: 
Calcium phosphide is dissolved in water. 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 15 Elements - The Nitrogen Family >> Oxoacids of Phosphorus

 Draw structures of the following: 
XeF

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 18 Elements - The Noble gas Family

 Draw structures of the following: 
`S_2O_8^{2-}`

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Oxoacids of Sulphur

 Give reactions for the following: 
O – O single bond is weaker than S – S single bond. 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family

 Tendency to show –3 oxidation state decrease from Nitrogn (N) to Bismuth (Bi).

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 15 Elements - The Nitrogen Family >> Oxides of Nitrogen

 Cl2 acts as a bleaching agent. 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 17 Elements - The Halogen Family

Write one difference between transition elements and p-block elements with reference to variability of oxidation states.

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Oxoacids of Sulphur

Write a chemical reaction to show that the open structure of D-glucose contains the following :  

Five alcohol groups

Appears in 1 question paper
Chapter: [7] Alcohols, Phenols and Ethers
Concept: Chemical Properties of Alcohols and Phenols

Why phenol undergoes electrophilic substitution more easily than benzene? 

Appears in 1 question paper
Chapter: [7] Alcohols, Phenols and Ethers
Concept: Chemical Reaction of Ethers - Electrophilic Substitution

Give a reason for the following :
Ozone is thermodynamically less stable than oxygen. 

Appears in 1 question paper
Chapter: [7] P - Block Elements
Concept: Group 16 Elements - The Oxygen Family >> Ozone
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