12th Chemistry - Book Back Answers - Unit 3 p-Block Elements-II - English Medium Guides

  

 

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Tamil Nadu Board 12th Standard Chemistry - Unit 3: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 3 from the Tamil Nadu State Board 12th 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 Unit 3 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 12 students! Prepare well and aim for top scores. Thank you!

I. Multiple Choice Questions

1. In which of the following , NH₃ is not used?

a) Nessler’s reagent

b) Reagent for the analysis of IV group basic radical

c) Reagent for the analysis of III group basic radical

d) Tollen’s reagent

Answer Key: 

a) Nessler’s reagent 

 

2. Which is true regarding nitrogen?

a) least electronegative element

b) has low ionisation enthalpy than oxygen

c) d- orbitals available

d) ability to form p$\mathbf{\pi }$−p$\mathbf{\pi }$ bonds with itself

Answer Key: 

d) ability to form p$\mathbf{\pi }$−p$\mathbf{\pi }$ bonds with itself

 

3. An element belongs to group 15 and 3 rd period of the periodic table, its electronic

configuration would be

a) 1s² 2s² 2p⁴

b) 1s² 2s² 2p³

c) 1s² 2s² 2p⁶ 3s² 3p²

d) 1s² 2s² 2p⁶ 3s² 3p³

Answer Key: 

d) 1s² 2s² 2p⁶ 3s² 3p³ 

  

4. Solid (A) reacts with strong aqueous NaOH liberating a foul smelling gas(B) which

spontaneously burn in air giving smoky rings. A and B are respectively

a) P₄(red) and PH₃

b) P₄(white) and PH₃

c) S₈ and H₂S

d) P₄(white) and H₂S

Answer Key: 

b) P₄(white) and PH₃ 

  

5. On hydrolysis, PCl₃ gives

a) H₃PO₃

b) PH₃

c) H₃PO₄

d) POCl₃

Answer Key: 

a) H₃PO₃ 

  

6. P₄O₆ reacts with cold water to give

a) H₃PO₃

b) H₄P₂O₇

c) HPO₃

d) H₃PO₄

Answer Key: 

a) H₃PO₃ 

  

7. The basicity of pyrophosphorous acid ( H₄P₂O₅) is

a) 4

b) 2

c) 3

d) 5

Answer Key: 

b) 2 

  

8. The molarity of given orthophosphoric acid solution is 2M. its normality is

a) 6N

b) 4N

c) 2N

d) none of these

Answer Key: 

a) 6N  

  

9. Assertion : bond dissociation energy of fluorine is greater than chlorine gas

    Reason : chlorine has more electronic repulsion than fluorine

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: 

d) Both assertion and reason are false. 

  

10. Among the following, which is the strongest oxidizing agent?

a) Cl₂

b) F₂

c) Br₂

d) l₂

Answer Key: 

b) F₂ 

  

11. The correct order of the thermal stability of hydrogen halide is

a) HI > HBr > HCl > HF

b) HF > HCl > HBr > HI

c) HCl > HF > HBr > HI

d) HI > HCl > HF > HBr

Answer Key: 

b) HF > HCl > HBr > HI 

  

12. Which one of the following compounds is not formed?

a) XeOF₄

b) XeO₃

c) XeF₂

d) NeF₂

Answer Key: 

d) NeF₂ 

  

13. Most easily liquefiable gas is

a) Ar

b) Ne

c) He

d) Kr

Answer Key: 

d) Kr 

  

14. XeF₆ on complete hydrolysis produces

a) XeOF₄

b) XeO₂F₂

c) XeO₃

d) XeO₂

Answer Key: 

c) XeO₃ 

  

15. Which of the following is strongest acid among all?

a) HI

b) HF

c) HBr

d) HCl

Answer Key: 

a) HI 

  

16. Which one of the following orders is correct for the bond dissociation enthalpy of

halogen molecules?

a) Br₂ > I₂ > F₂ > Cl₂

b) F₂ > Cl₂ > Br₂ > l₂

c) I₂ > Br₂ > Cl₂ > F₂

d) Cl₂ > Br₂ > F₂ > I₂

Answer Key: 

d) Cl₂ > Br₂ > F₂ > I₂ 

  

17. Among the following the correct order of acidity is

a) HClO₂ < HClO < HClO₃ < HClO₄

b) HClO₄ < HClO₂ < HClO < HClO₃

c) HClO₃ < HClO₄ < HClO₂ < HClO

d) HClO < HClO₂ < HClO₃ < HClO₄

Answer Key: 

d) HClO < HClO₂ < HClO₃ < HClO₄ 

  

18. When copper is heated with conc HNO3 it produces

a) Cu(NO₃)₂ , NO and NO₂

b) Cu(NO₃)₂ and N₂O

c) Cu(NO₃)₂ and NO₂

d) Cu(NO₃)₂ and NO

Answer Key:  

c) Cu(NO₃)₂ and NO₂ 

 

 

II. Short Answer Questions.

12th Chemistry

III. Long Answer Questions. 

12th Chemistry

IV. Exercise.   

12th Chemistry