SOLUTIONS QUIZ 11

 

  SOLUTIONS Quiz-11

Dear Readers,

The one subject in NEET which is candidates who can easily attain good marks is Chemistry. That's the reason, often, one doesn’t pay notice and choose to compromise it. But if one wants to rank above others, the tip is to be thorough with NEET chemistry concepts. The understanding of reactions and definite basic understanding is what requires major attention in Chemistry but once done it only gets simpler from there. The main focus on the to-do list should be on getting a hang of the NCERT syllabus of NEET chemistry.

advanced. .

Q1.  An aqueous solution of methanol in water has vapour pressure

•   Less than that of water
•   More than that of water
•   Equal to that of water
•   Equal to that of methanol

Solution
Methanol has low boiling point than H2O, lower is boiling point of solvent more is vapour pressure

Q2. The condition for the validity of Henry’s law are :

•   The pressure should not be too high
•   The temperature should not be too low
•   The gas should neither dissociate not enter into chemical combination with solvent
•   All of the above

Solution
All are conditions for Henry’s law

Q3.   The osmatic pressure of 0.4% urea solution is 1.66 atm. and that of a solutions of sugar of 3.42% is 2.46 atm. When both the solutions are mixed then the osmatic pressure of the resultant solution will be

•   1.02 atm
•   2.06 atm
•   3.04 atm
•   0.02 atm

Solution
𝜋 = 1.66 + 2.46 / 2 = 2.06 atm

Q4.  . Elevation in boiling point was 0.52℃ when 6 g of a compound was dissolved in 100 g of water. Molecular weight of X is (𝑘_b 𝑜𝑓 water is 5.2℃ per 100 g water )

•   120
•   60
•   600
•   180

Solution
M= 100×𝑘𝑏×𝑤 ∆𝑇𝑏×𝑊 

 Given, 𝑘𝑏 = 5.2 

 w = mass of solute = 6 g 

W =mass of solvent =100 g 

 ∆𝑇𝑏 = elevation in boiling point = 0.52℃

 M = molecular weight =? 

∴M= 100×5.2×6 / 0.52×100 = 60

Q5. When a crystal of the solute is introduced into a super saturated solution of the solute :

•   The solute dissolves
•   The excess solute crystallizes out
•   The solution becomes unsaturated
•   The solution remains super saturated

Solution
  Super saturated state is a meta stable state. .

Q6.  Which of the following solutions will have the highest boiling point?

•   0.1 M BaCl2
•   0.1 M FeCl3
• 0.1 M NaCl
•   0.1 M urea

Solution
As concentration of particles is maximum in FeCl3 solution so deviation in boiling point will be maximum. Hence, actual boiling point will be highest

Q7. Two solutions have different osmotic pressure. The solution of lower osmotic pressure is called :  

 

•   Isotonic solution
•   Hypertonic solution
•   Hypotonic solution
•   none of these

Solution
In a pair of two solution, the one having higher osmotic pressure is called hypertonic and the other having lower osmotic pressure is called hypotonic

Q8. Molecular weight of glucose is 180. A solution of glucose which contains 18 g/L, is

•   0.1 molal
• 0.2 molal
•   0.3 molal
•   0.4 molal

Molality = 18/180 = 0.1 molal

Q9. Azeotropic mixture of HCl and water has

•   48% HCl
•   22.2% HCl
•   36% HCl
•   20.2% HCl

Solution
Azeotropic mixture of HCl and water has 20.24% of HCl. It boils at 108.5℃ under a pressure of one atmosphere

Q10.  Depression in freezing point is 6 K for NaCl solution if 𝑘𝑓 for water is 1.86 K/kg mol, amount of NaCl dissolved in 1 kg water is  

 

•   3.42
•   1.62
•   3.24
•   1.71

Solution
∆𝑇𝑓 = 𝑖 ×𝑘_f × 𝑛 𝑊 × 1000 

 6=2× 1.86 ×𝑛/1× 1 

 𝑛 = 6/2 × 1.86 = 1.62