11th Chemistry - Book Back Answers - Unit 1 - English Medium Guides

  

 

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Tamil Nadu Board 11th Standard Chemistry - Unit 1: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 1 – 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 1 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 1:Basic Concepts of Chemistry and Chemical Calculations

I. Choose the best answer.

1. 40 ml of methane is completely burnt using 80 ml of oxygen at room       

temperature The volume of gas left after cooling to room temperature is

(a) 40 ml CO₂ gas

(b) 40 ml CO₂ gas and 80 ml H₂O gas

(c) 60 ml CO₂  gas and 60 ml H₂O gas

(d) 120 ml CO₂ gas 

Answer Key 

(a) 40 ml CO₂ gas 

2. An element X has the following isotopic composition ²⁰⁰X = 90%, ¹⁹⁹ X = 8 % and  ²⁰² X = 2% .The weighted average atomic mass of the element X is closest to

(a) 201 u

(b) 202 u

(c) 199 u

(d) 200 u

Answer Key

(d) 200 u 

  

3. Assertion: Two mole of glucose contains 12.044 x10²³ molecules of glucose

Reason : Total number of entities present in one mole of any substance is equal to 6.02 x10²²

(a) both assertion and reason are true and the 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 

(c) assertion is true but reason is false

 

4. Carbon forms two oxides, namely carbon monoxide and carbon dioxide. The equivalent mass of which element remains constant?

(a) Carbon

(b) oxygen

(c) both carbon and oxygen

(d) neither carbon nor oxygen

Answer Key 

(b) oxygen  

 

5. The equivalent mass of a trivalent metal element is 9 g eq^-1 the molar mass of its anhydrous oxide is

(a) 102 g

(b) 27 g

(c) 270 g

(d) 78 g

Answer Key 

(a) 102 g

 

6.The number of water molecules in a drop of water weighing 0.018 g is

(a) 6.022 x10²⁶

(b) 6.022 x10²³

(c) 6.022 x10²⁰

(d) 9.9 x10²²

Answer Key

(c) 6.022 x10²⁰ 

  

7. 1 g of an impure sample of magnesium carbonate (containing no thermally decomposable impurities) on complete thermal decomposition gave 0.44 g of carbon dioxide gas. The percentage of impurity in the sample is

(a) 0%

(b) 4.4%

(c) 16%

(d) 8.4% 

Answer Key

(c) 16% 

  

8. When 6.3 g of sodium bicarbonate is added to 30 g of acetic acid solution, the residual solution is found to weigh 33 g. The number of moles of carbon dioxide released in the reaction is

(a) 3

(b) 0.75

(c) 0.075

(d) 0.3

Answer Key 

(c) 0.075

   

9. When 22.4 litres of H₂(g) is mixed with 11.2 litres of Cl₂ (g), each at 273 K at 1 atm the moles of HCl (g), formed is equal to

(a) 2 moles of HCl (g)

(b) 0.5 moles of HCl (g)

(c) 1.5 moles of HCl (g)

(d) 1 moles of HCl (g)

Answer Key

(d) 1 moles of HCl (g) 

 

10. Hot concentrated sulphuric acid is a moderately strong oxidising agent. Which of the following reactions does not show oxidising behaviour?

(a) Cu + 2H₂SO₄→ CuSO₄ + SO₂+2H₂O

(b) C + 2H₂SO₄ ← CO₂ +2SO₂ + 2H₂O

(c) BaCl₂ + H₂SO₄ ← BaSO₄+2HCl

(d) none of the above

Answer Key

(c) BaCl₂ + H₂SO₄ ← BaSO₄+2HCl

 

11. Choose the disproportionation reaction among the following redox reactions.

(a) 3Mg(s) + N₂(g) → Mg₃N₂(s)

(b) P₄(s)+3NaOH+3H₂O → PH₃(g)+3NaH₂PO₂(aq)

(c) Cl₂(g) + 2KI(aq) ← 2KCl(aq) + I₂

(d) Cr₂O₃(s) + 2Al(s) → Al₂O₃(s) + 2Cr(s)

Answer Key

(b) P₄(s)+3NaOH+3H₂O → PH₃(g)+3NaH₂PO₂(aq)

 

12. The equivalent mass of potassium permanganate in alkaline medium is

MnO₄ ^-+ 2H₂O+3e^- →MnO₂+4OH^-

(a) 31.6

(b) 52.7

(c) 79

(d) None of these

Answer Key

(b) 52.7   

 

13. Which one of the following represents 180g of water?

(a) 5 Moles of water

(b) 90 moles of water

(c) $\frac{6.022X{10}^{23}}{180}$ molecules of water

(d) 6.022 x10²⁴ molecules of water

Answer Key

(c) $\frac{6.022X{10}^{23}}{180}$ molecules of water  

 

14. 7.5 g of a gas occupies a volume of 5.6 litres at $0^{\mathrm{o}}$ C and 1 atm pressure. The gas is

(a) NO

(b) N₂O

(c) CO

(d) CO₂

Answer Key

(a) NO 

 

15. Total number of electrons present in 1.7 g of ammonia is

(a) 6.022 x10²³

(b) $\frac{6.022\mathrm{x}{10}^{22}}{1.7}$

(c) $\frac{6.022\mathrm{x}{10}^{24}}{1.7}$

(d) $\frac{6.022\mathrm{x}{10}^{23}}{1.7}$

Answer Key

(a) 6.022 x10²³ 

 

16. The correct increasing order of the oxidation state of sulphur in the anions

SO₄^2-,SO₃^2-,S₂O₄^2-,S₂O₆^2- is

(a)SO₃^2- < SO₄^2-<S₂O₄^2-<S₂O₆^2-

(b) SO₄^2-< S₂O₄^2-< S₂O₆^2-< SO₃^2-

(c) S₂O₄^2-< SO₃^2-< S₂O₆^2-< SO₄^2-

(d) S₂O₆^2-< S₂O₄^2-< SO₄^2-< SO₃^2-

Answer Key

(c) S₂O₄^2-< SO₃^2-< S₂O₆^2-< SO₄^2- 

 

17. The equivalent mass of ferrous oxalate is

(a)$\frac{\mathrm{molar} \mathrm{mass} \mathrm{of} \mathrm{ferrous} \mathrm{oxalate}}{1}$

(b)$\frac{\mathrm{molar} \mathrm{mass} \mathrm{of} \mathrm{ferrous} \mathrm{oxalate}}{2}$

(c)$\frac{\mathrm{molar} \mathrm{mass} \mathrm{of} \mathrm{ferrous} \mathrm{oxalate}}{3}$

(d)the mass of one mole of carbon

Answer Key

(d)the mass of one mole of carbon 

  

18. If Avogadro number were changed from 6.022x10²³ to 6.022 x10²⁰,this would change

(a) the ratio of chemical species to each other in a balanced equation

(b) the ratio of elements to each other in a compound

(c) the definition of mass in units of grams

(d) the mass of one mole of carbon

Answer Key 

(d) the mass of one mole of carbon 

 

19. Two 22.4 litre containers A and B contains 8 g of O₂ and 8 g of SO₂ respectively at 273 K and 1 atm pressure, then

(a) Number of molecules in A and B are same

(b) Number of molecules in B is more than that in A.

(c) The ratio between the number of molecules in A to number of molecules in B is 2:1

(d) Number of molecules in B is three times greater than the number of molecules in A.

Answer Key

(c) The ratio between the number of molecules in A to number of molecules in B is 2:1 

 

20. What is the mass of precipitate formed when 50 ml of 8.5 % solution of AgNO₃ is mixed with 100 ml of 1.865 % potassium chloride solution?

(a) 3.59 g

(b) 7 g

(c) 14 g

(d) 28 g

Answer Key

(a) 3.59 g 

 

21. The mass of a gas that occupies a volume of 612.5 ml at room temperature and pressure (${25}^{\mathrm{o}}$C and 1 atm pressure) is 1.1g. The molar mass of the gas is

(a) 66.25gmol^-1

(b) 44gmol^-1

(c) 24.5gmol^-1

(d) 662.5gmol^-1

Answer Key

(b) 44gmol^-1 

  

22. Which of the following contain same number of carbon atoms as in 6 g of carbon-12.

(a) 7.5 g ethane

(b) 8 g methane

(c) both (a) and (b)

(d) none of these

Answer Key

(c) both (a) and (b) 

 

23. Which of the following compound(s) has/have percentage of carbon same as that in ethylene (C₂H₄)

(a) propene

(b) ethyne

(c) benzene

(d) ethane

Answer Key

(a) propene  

24. Which of the following is/are true with respect to carbon -12.

(a) relative atomic mass is 12 u

(b) oxidation number of carbon is +4 in all its compounds.

(c) 1 mole of carbon-12 contain 6.022x10²² carbon atoms.

(d) all of these

Answer Key

(a) relative atomic mass is 12 u  

25. Which one of the following is used as a standard for atomic mass.

(a) ₆C¹²

(b) ₇C¹²

(c) ₆C¹³

(d) ₆C¹⁴

Answer Key

(a) ₆C¹² 

II. Short Answer Questions

11th Chemistry

III. Long Answer Questions

11th Chemistry

IV. Exercise

11th Chemistry