Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Write down the reaction taking place in blast furnace related to the metallurgy of iron in the temperature rnge 500 K – 800 K. What is the role of limestone in the metallurgy of iron? 

What happens when Silver is leached with NaCN in the presence of air? 

What happens when Copper matte is charged into silica lined converter and hot air blast is blown? 

What happens when NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method? 

 Write the electronic configuration of Fe(III) on the basis of crystal field theory when it forms an octahedral complex in the presence of (i) strong field, and (ii) weak field ligand. (Atomic no.of Fe=26) 

Differentiable between the following: 
Essential amino acids Non-essential amino acids 

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

E⁰ value for  Mn³⁺ Mn²⁺ couple is much more positive than that for Cr^3-/ Cr^2-.

 Write the chemical equation for the preparation of 4 KMnO from 2. MnO Why does purple colour of acidified permanganate solution decolourise when it oxidises Fe^2- to Fe³⁺ ? 

 Write the ionic equation showing the oxidation of Fe(II) salt by acidified dichromate solutions. 

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).

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

An element crystallizes in fcc lattice with a cell edge of 300 pm. The density of the element is 10.8 g cm^-3. calculate the number of atoms in 108 g  of the element.

Name the method of refining which is Used to obtain semiconductor of high purity. 

Name the method of refining which is Used to obtain low boiling metal.

How do you convert the following:

Ethanol to Propan-2-ol

Write the mechanism of the following reaction : 

\[\ce{C2H5OH->[H2SO4][443K]CH2=CH2 + H2O}\]

An element crystallizes in fcc lattice with a cell edge of 300 pm. The density of the element is 10.8 g cm⁻³. Calculate the number of atoms in 108 g of the element.

Give simple chemical test to distinguish between Ethanol and Phenol.

Substances that alter the rate of a chemical reaction without being used up in a chemical reaction is known as ____________.