Subject

Chemistry

Class

CBSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.

 Multiple Choice QuestionsShort Answer Type

1.

Complete the following reactions :
NH3 + 3Cl2(excess) →


NH3 + 3Cl2(excess) → NCl3 + 3HCl

4122 Views

2.

What happens when
(NH4)2Cr2O7 is heated?


Ammonium dichromate, (NH4)2Cr2O7, decomposes when heated to produce N2, H2O, and Cr2O3

(NH4)2Cr2O7  + heat →N2 + 4H2O + Cr2O3

3652 Views

3.

Define the following terms:
Molality (m)


Molality of a solution is defined as the number of moles of solute dissolved per kg of solvent.

Molality space left parenthesis straight m right parenthesis space equals space fraction numerator No. space of space moles space of space solute over denominator Mass space of space solvent space left parenthesis in space grams right parenthesis end fraction space straight x space 1000

1349 Views

4.

For a reaction R → P, half-life (t1/2) is observed to be independent of the initial concentration of reactants. What is the order of reaction?


First order reaction.

2593 Views

5.

Write one similarity between Physisorption and Chemisorption?


(i) Physisorption and Chemisorption both are a surface phenomenon.
(ii) Physisorption and Chemisorption both increase with increase in surface area

3174 Views

6.

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


The formula of an oxo anion of Manganese in which it shows the oxidation state equal to its group member is Permanganate MnO/KMnO4

The oxidation state of Mn is + 7.

10613 Views

7.

Define the following terms:
Colligative properties


Colligative properties are properties of solutions that depend on the ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the nature of the chemical species present.Colligative properties include vapour pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.

1551 Views

8.

What happens when
H3PO3 is heated?


Phosphorous acid H3PO3, on heating, undergoes disproportionation reaction to form Phosphine (PH3) and Phosphoric acid (H3PO4)

4H3PO3 +heat → 3H3PO4 +PH3

1750 Views

9.

Draw the structures of the following :
H2S2O7


Pyrosulfuric acid (oleum)

1996 Views

10.

Complete the following reactions :
XeF6 + 2H2O → 


XeF6 + 2H2O → XeO2F2 + 4HF

3243 Views