11th Chemistry - Book Back Answers - Unit 9 - English Medium Guides

 

 

Plus One / 11th Chemistry- Book Back Answers - Unit 9 - English Medium

Tamil Nadu Board 11th Standard Chemistry - Unit 9 : Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 9 – Chemistry from the Tamil Nadu State Board 11th Standard Chemistry textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Chemistry Unit 9 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 11 students! Prepare well and aim for top scores. Thank you!

Unit 9 :Solutions

I. Choose the best answer.

1.The molality of a solution containing 1.8g of glucose dissolved in 250g of water is
a) 0.2 M
b) 0.01 M
c) 0.02 M
d) 0.04 M
Answer Key:
d) 0.04 M
 
2.Which of the following concentration terms is / are independent of temperature
a) molality
b) molarity
c) mole fraction
d) (a) and (c)
Answer Key:
d) (a) and (c)
   
3. Stomach acid, a dilute solution of HCl can be neutralised by reaction with Aluminium hydroxide
Al (OH)₃ + 3HCl (aq) → AlCl₃ + 3 H₂O
How many millilitres of 0.1 M Al(OH)₃ solution are needed to neutralise 21 mL of 0.1 M HCl?
a) 14 mL
b) 7 mL
c) 21 mL
d) none of these
Answer Key:
b) 7 mL
 
4. The partial pressure of nitrogen in air is 0.76 atm and its Henry's law constant is 7.6 × 10⁴ atm at 300K. What is the molefraction of nitrogen gas in the solution obtained when air is bubbled through water at 300K?
a) 1 × 10^–4
b) 1 × 10^–6
c) 2 × 10^–5
d) 1 × 10^–5
Answer Key:
d) 1 × 10^–5
  
5. The Henry's law constant for the solubility of Nitrogen gas in water at 350 K is 8 × 10⁴ atm. The mole fraction of nitrogen in air is 0.5. The number of moles of Nitrogen from air dissolved in 10 moles of water at 350K and 4 atm pressure is
a) 4 × 10^–4
b) 4 × 10⁴
c) 2 × 10^–2
d) 2.5 × 10^–4
Answer Key:
d) 2.5 × 10^–4
   
6. Which one of the following is incorrect for ideal solution?

a) $\mathrm{\Delta }$H_mix = 0
b) $\mathrm{\Delta }$U_mix = 0
c) $\mathrm{\Delta }$P = P _observed – P _{Calculated by raoults law} = 0
d) $\mathrm{\Delta }$G_mix = 0
Answer Key:
d) $\mathrm{\Delta }$G_mix = 0

   
7. Which one of the following gases has the lowest value of Henry's law constant ?
a) N₂
b) He
c) CO₂
d) H₂
Answer Key:
c) CO₂   
 
8. P₁ and P₂ are the vapour pressures of pure liquid components, 1 and 2 respectively of an ideal binary solution if x₁ represents the mole fraction of component 1, the total pressure of the solution formed by 1 and 2 will be
a) P₁ + x₁ (P₂ – P₁)
b) P₂ – x₁ (P₂ + P₁)
c) P₁ – x₂ (P₁ – P₂)
d) P₁ + x₂ (P₁ – P₂)
Answer Key:
c) P₁ – x₂ (P₁ – P₂)
   
9. Osometic pressure ($\mathrm{\pi }$) of a solution is given by the relation
a) $\mathrm{\pi }$ = nRT
b) $\mathrm{\pi }$V = nRT
c) $\mathrm{\pi }$RT = n
d) none of these
Answer Key:
b) $\mathrm{\pi }$V = nRT
   
10. Which one of the following binary liquid mixtures exhibits positive deviation from Raoults law ?
a) Acetone + chloroform
b) Water + nitric acid
c) HCl + water
d) ethanol + water
Answer Key:
d) ethanol + water
 
11. The Henry's law constants for two gases A and B are x and y respectively. The ratio of mole fractions of A to B is 0.2. The ratio of mole fraction of B and A dissolved in water will be
a)$\frac{\mathrm{ 2}\mathrm{x}}{\mathrm{y}}$
b)$\frac{\mathrm{ y}}{0.2\mathrm{x}}$
c)$\frac{\mathrm{ x}}{0.2\mathrm{y}}$
d)$\frac{\mathrm{ 5}\mathrm{x}}{\mathrm{y}}$
Answer Key:
d)$\frac{\mathrm{ 5}\mathrm{x}}{\mathrm{y}}$
  
12. At ${100}^{\circ }\mathrm{C}$ the vapour pressure of a solution containing 6.5g a solute in 100g water is 732mm. If K_b = 0.52, the boiling point of this solution will be
a) ${102}^{\circ }\mathrm{C}$ 
b) ${100}^{\circ }\mathrm{C}$ 
c) ${101}^{\circ }\mathrm{C}$ 
d)${100.52}^{\circ }\mathrm{C}$ 
Answer Key:
c) ${101}^{\circ }\mathrm{C}$ 

13. According to Raoults law, the relative lowering of vapour pressure for a solution is equal to 
a) mole fraction of solvent 
b) mole fraction of solute 
c) number of moles of solute 
d) number of moles of solvent
Answer Key:
b) mole fraction of solute 

14. At same temperature, which pair of the following solutions are isotonic ?
a) 0.2 M BaCl₂ and 0.2M urea
b) 0.1 M glucose and 0.2 M urea
c) 0.1 M NaCl and 0.1 M K₂SO₄
d) 0.1 M Ba (NO₃)₂ and 0.1 M Na₂ SO₄
Answer Key:
d) 0.1 M Ba (NO₃)₂ and 0.1 M Na₂ SO₄
  
15. The empirical formula of a non-electrolyte(X) is CH₂O. A solution containing six gram of X exerts the same osmotic pressure as that of 0.025M glucose solution at the same temperature. The molecular formula of X is
a) C₂H₄O₂
b) C₈H₁₆O₈
c) C₄H₈O₄
d) CH₂O
Answer Key:
b) C₈H₁₆O₈
 
16. The K_H for the solution of oxygen dissolved in water is 4 × 10⁴ atm at a given temperature. If the partial pressure of oxygen in air is 0.4 atm, the mole fraction of oxygen in solution is
a) 4.6 × 10³
b) 1.6 × 10⁴
c) 1 × 10^–5
d) 1 × 10⁵
Answer Key:
c) 1 × 10^–5
 
17. Normality of 1.25M sulphuric acid is
a) 1.25 N
b) 3.75 N
c) 2.5 N
d) 2.25 N
Answer Key:
c) 2.5 N
 
18. Two liquids X and Y on mixing gives a warm solution. The solution is
a) ideal
b) non-ideal and shows positive deviation from Raoults law
c) ideal and shows negative deviation from Raoults Law
d) non-ideal and shows negative deviation from Raoults Law
Answer Key:
d) non-ideal and shows negative deviation from Raoults Law
 
19. The relative lowering of vapour pressure of a sugar solution in water is 3.5× 10^–3. The mole fraction of water in that solution is
a) 0.0035 

b) 0.35
c) 0.0035 / 18
d) 0.9965
Answer Key:
d) 0.9965
  
20. The mass of a non-voltaile solute (molar mass 80 g mol^–1) which should be dissolved in 92g of toluene to reduce its vapour pressure to 90%
a) 10g
b) 20g
c) 9.2 g
d) 8.89g
Answer Key:
d) 8.89g
 
21. For a solution, the plot of osmotic pressure ($\mathrm{\pi }$) verses the concentration (c in mol L^–1) gives a straight line with slope 310R where 'R' is the gas constant. The temperature at which osmotic pressure measured is
a) 310 × 0.082 K
b) ${310}^{\circ }\mathrm{C}$
c) ${37}^{\circ }\mathrm{C}$
d)$\frac{\mathrm{ 310}}{0.082}\mathrm{K}$
Answer Key:
c) ${37}^{\circ }\mathrm{C}$
 
22. 200ml of an aqueous solution of a protein contains 1.26g of protein. At 300K, the osmotic pressure of this solution is found to be 2.52 × 10^–3 bar. The molar mass of protein will be (R = 0.083 L bar mol^–1 K^–1)
a) 62.22 Kg mol^–1
b) 12444g mol^–1
c) 300g mol^–1
d) none of these
Answer Key:
a) 62.22 Kg mol^–1
 
23. The Van't Hoff factor (i) for a dilute aqueous solution of the strong Electrolyte barium hydroxide is (NEET)
a) 0
b) 1
c) 2
d) 3
Answer Key:
b) 1
 
24. What is the molality of a 10% W/W aqueous sodium hydroxide solution ?
a) 2.778
b) 2.5
c) 10
d) 0.4
Answer Key:
b) 2.5
 
25. The correct equation for the degree of an associating solute, 'n' molecules of which undergoes association in solution, is
a) $\mathrm{\alpha }=\frac{\mathrm{n}(\mathrm{i}-1)}{\mathrm{n}-1}$
b) ${\mathrm{\alpha }}^2=\frac{\mathrm{n}(1-\mathrm{i})}{\mathrm{n}-1}$
c) $\mathrm{\alpha }=\frac{\mathrm{n}(\mathrm{i}-1)}{\mathrm{1}-\mathrm{n}}$
d) $\mathrm{\alpha }=\frac{\mathrm{n}(\mathrm{n}-1)}{(\mathrm{n}-1)}$
Answer Key:
c) $\mathrm{\alpha }=\frac{\mathrm{n}(\mathrm{i}-1)}{\mathrm{1}-\mathrm{n}}$

26. Which of the following aqueous solutions has the highest boiling point ?
a) 0.1M KNO₃
b) 0.1 MNa₃PO₄
c) 0.1 M BaCl₂
d) 0.1 M K₂SO₄
Answer Key:
b) 0.1 MNa₃PO₄
 
27. The freezing point depression constant for water is 1.86${\circ }^{}\mathrm{C}$ K Kgmol^-1. If 5g Na₂SO₄ is dissolved in 45g water, the depression in freezing point is 3.64oC. The Vant Hoff factor for Na₂SO₄ is
a) 2.50
b) 2.63
c) 3.64
d) 5.50
Answer Key:
a) 2.50

28. Equimolal aqueous solutions of NaCl and KCl are prepared. If the freezing point of NaCl is –$$2∘C , the freezing point of KCl solution is expected to be
a) –2${\circ }^{}\mathrm{C}$
b) –4${\circ }^{}\mathrm{C}$
c) –1${\circ }^{}\mathrm{C}$
d) 0${\circ }^{}\mathrm{C}$
Answer Key:
a) –2${\circ }^{}\mathrm{C}$

29. Phenol dimerises in benzene having van't Hoff factor 0.54. What is the degree of association ?
a) 0.46
b) 92
c) 46
d) 0.92
Answer Key:
d) 0.92
 
30. Assertion : An ideal solution obeys Raoults Law
Reason : In an ideal solution, solvent-solvent as well as solute-solute interactions are similar to solute-solvent interactions.
a) both assertion and reason are true and reason is the correct explanation of
assertion
b) both assertion and reason are true but reason is not the correct explanation of
assertion
c) assertion is true but reason is false
d) both assertion and reason are false
Answer Key:
a) both assertion and reason are true and reason is the correct explanation of
assertion

 

II. Short Answer Questions

11th Chemistry

III. Long Answer Questions

11th Chemistry

IV. Exercise

11th Chemistry