Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

Give reasons for the following :

Aquatic animals are more comfortable in the cold water than in warm water.

Write the chemical reactions involved in the process of extraction of Gold. Explain the role of dilute NaCN and Zn in this process.

Write the product when D-glucose reacts with conc. HNO₃.

Give reason (CH₃)₂NH is more basic than (CH₃)₃N in an aqueous solution.

An element 'X' (At. mass = 40 g mol^-1) having f.c.c. the structure has unit cell edge length of 400 pm. Calculate the density of 'X' and the number of unit cells in 4 g of 'X'. (N_A = 6.022 × 10²³ mol^-1)

 Arrange the following in the increasing order of their pK_b values:

C₆H₅NH₂, C₂H₅NH₂, C₆H₅NHCH₃

Which allotrope of sulphur is thermally stable at room temperature ?

Why is Butan-1-ol optically inactive but Butan-2-ol is optically active?

Draw the geometrical isomers of complex [Pt(en)₂Cl₂]²⁺.

What is the role of dilute NaCN in the extraction of gold ?

Illustrate the following reactions giving suitable example in each case 

Ammonolysis

Write the structures of main products when benzene diazonium chloride (C6 H5 N+2CI−)C6 H5 N2+CI- reacts with the  :  HBF₄/∆

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

Which reducing agent is employed to get copper from the leached low-grade copper ore?

Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?

State Henry's Law. What is the effect of temperature on the solubility of a gas in a liquid?

Arrange the following in increasing order of basic strength :

C₆H₅NH₂, C₆H₅NHCH₃, C₆H₅N(CH₃)₂

What happens when Phenol is oxidised with Na₂Cr₂O₇/H⁺?

Differentiable between the following: 
Amylose and Amylopectin 

Define order of reaction. How does order of a reaction differ from molecularity for a complex reaction?