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

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 ____________.

Zinc carbonate is precipitated from zinc sulphate solution by the addition of ___________.

Which two of the following salts are used for preparing iodized salt?

(i) KIO₃

(ii) KI

(iii) I₂

(iv) HI

Among the following the one which reacts most readily with ethanol is:

Methanol and ethanol are miscible in water due to ____________.

If ethanol dissolves in water, then which of the following would be observed:

Which of the following is correct?