Science (English Medium) कक्षा १२ - CBSE Important Questions for Chemistry

 Predict whether van’t Hoff factor, (i) is less than one or greater than one in the following: 
CH₃COOH dissolved in water 

 A solution 0.1 M of Na₂SO₄ is dissolved to the extent of 95%. What would be its osmotic pressure at 027 ? C (R = 0.0821 L atm K^-1 mol^-1) .

 An element crystallises in bcc lattic with a cell edge of 3 × 10^-8cm. The density of the element is 6.89 g cm^-3 . calculate the molar mass of element. (N_A = 6.022 × 10²³ mol^-1)

What type of semiconductor is obtained when 
Ge is doped with In?

 What type of semiconductor is obtained when 
 Si is doped with P? 

Out of NaCl and AgCl, which one shows Frenkel defect and why? 

Arrange the following in increasing order of boiling points:

(CH₃)₃ N, C₂ H₅ OH, C₂ H₅ NH₂

State Raoult’s law for a solution containing volatile components. Write two characteristics of the solution which obey Raoult’s law at all concentrations. 

Out of [CoF₆]^3- and [Co(en)₃]³⁺, which one complex is
(i) paramagnetic
(ii) more stable
(iii) inner orbital complex and
(iv) high spin complex
(Atomic no. of Co = 27) 

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.

A 4% solution(w/w) of sucrose (M = 342 g mol^–1) in water has a freezing point of 271.15 K. Calculate the freezing point of 5% glucose (M = 180 g mol^–1) in water.
(Given: Freezing point of pure water = 273.15 K) 

Account for the following : 

o-nitrophenol is more steam volatile than p-nitrophenol.  

Give reason for the following :  
Sulphur in vapour state shows paramagnetic behaviour. 

Write the name of gas released when Cu is added to dilute HNO₃

Write the name of gas released when Cu is added to the conc. HNO₃ 

Arrange the following in decreasing order of solubility in water:
\[\ce{(CH3)3N,(CH3)2NH,CH3NH2}\]

Answer the following question.
What type of stoichiometric defect is shown by ZnS and why?

A 4% solution(w/w) of sucrose (M = 342 g mol⁻¹) in water has a freezing point of 271.15 K. Calculate the freezing point of 5% glucose (M = 180 g mol⁻¹) in water.
(Given: Freezing point of pure water = 273.15 K)

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.

Which of the following is not a characteristic of a crystalline solid?