12th Chemistry - Book Back Answers - Unit 4 Transition And Inner Transition Elements

Plus Two / 12th Chemistry - Book Back Answers - Unit 4 English Medium

Tamil Nadu Board 12th Standard Chemistry - Unit 4: Book Back Answers and Solutions

This post covers the book back answers and solutions for Unit 4 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 4 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. Sc( Z=21) is a transition element but Zinc (z=30) is not because

a) both Sc³⁺ and Zn²⁺ ions are colourless and form white compounds.

b) in case of Sc, 3d orbital are partially filled but in Zn these are completely filled

c) last electron as assumed to be added to 4s level in case of zinc

d) both Sc and Zn do not exhibit variable oxidation states

Answer Key:

b) in case of Sc, 3d orbital are partially filled but in Zn these are completely filled

2. Which of the following d block element has half filled penultimate d sub shell as well as half filled valence sub shell?

a) Cr

b) Pd

c) Pt

d) none of these

Answer Key:

a) Cr

3. Among the transition metals of 3d series, the one that has highest negative asas

standard electrode potential is

a) Ti

b) Cu

c) Mn

d) Zn

Answer Key:

a) Ti

4. Which one of the following ions has the same number of unpaired electrons as present in V³⁺?

a) Ti³⁺

b) Fe³⁺

c) Ni²⁺

d) Cr³⁺

Answer Key:

c) Ni²⁺

5. The magnetic moment of Mn²⁺ ion is

a) 5.92BM

b) 2.80BM

c) 8.95BM

d) 3.90BM

Answer Key:

a) 5.92BM

6. The catalytic behaviour of transition metals and their compounds is ascribed

mainly due to

a) their magnetic behaviour

b) their unfilled d orbitals

c) their ability to adopt variable oxidation states

d) their chemical reactivity

Answer Key:

c) their ability to adopt variable oxidation states

7. The correct order of increasing oxidizing power in the series

a) VO₂⁺< Cr₂O₇^2- < MnO₄^-

b) Cr₂O₇^2- < VO₂⁺ < MnO₄^-

c) Cr₂O₇^2- < MnO₄^- < VO₂⁺

d) MnO₄^- < Cr₂O₇^2- < VO₂⁺

Answer Key:

a) VO₂⁺< Cr₂O₇^2- < MnO₄^-

8. In acid medium, potassium permanganate oxidizes oxalic acid to

a) oxalate

b) Carbon dioxide

c) acetate

d) acetic acid

Answer Key:

b) Carbon dioxide

9. Which of the following statements is not true?

a) on passing H₂S, through acidified K₂Cr₂O₇ solution, a milky colour is observed.

b) Na₂Cr₂O₇ is preferred over K₂Cr₂O₇ in volumetric analysis

c) K₂Cr₂O₇ solution in acidic medium is orange in colour

d) K₂Cr₂O₇ solution becomes yellow on increasing the PH beyond 7

Answer Key:

b) Na₂Cr₂O₇ is preferred over K₂Cr₂O₇ in volumetric analysis

10. Permanganate ion changes to ________ in acidic medium

a) MnO₄^2-

b) Mn²⁺

c) Mn3+

d) MnO₂

Answer Key:

b) Mn²⁺

11. How many moles of I2 are liberated when 1 mole of potassium dichromate react with potassium iodide?

a) 1

b) 2

c) 3

d) 4

Answer Key:

c) 3

12. The number of moles of acidified KMnO₄ required to oxidize 1 mole of ferrous oxalate(FeC₂O₄) is

a) 5

b) 3

c) 0.6

d) 1.5

Answer Key:

c) 0.6

13. Which one of the following statements related to lanthanons is incorrect?

a) Europium shows +2 oxidation state.

b) The basicity decreases as the ionic radius decreases from Pr to Lu.

c) All the lanthanons are much more reactive than aluminium.

d) Ce⁴⁺solutions are widely used as oxidising agents in volumetric analysis.

Answer Key:

c) All the lanthanons are much more reactive than aluminium.

14. Which of the following lanthanoid ion is diamagnetic?

a) Eu²⁺

b) Yb²⁺

c) Ce²⁺

d) Sm²⁺

Answer Key:

b) Yb²⁺

15. Which of the following oxidation state is most common among the lanthanoids?

a) +4

b) +2

c) +5

d) +3

Answer Key:

d) +3

16. Assertion : Ce⁴⁺ is used as an oxidizing agent in volumetric analysis.

Reason: Ce⁴⁺ has the tendency of attaining +3 oxidation state.

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.

17. The most common oxidation state of actinoids is

a) +2

b) +3

c) +4

d) +6

Answer Key:

b) +3

18. The actinoid elements which show the highest oxidation state of +7 are

a) Np, Pu ,Am

b) U, Fm, Th

c) U, Th, Md

d) Es, No, Lr

Answer Key:

a) Np, Pu ,Am

19. Which one of the following is not correct?

a) La(OH)₃ is less basic than Lu(OH)₃

b) In lanthanoid series ionic radius of Ln³⁺ ions decreases

c) La is actually an element of transition metal series rather than lanthanoid series

d) Atomic radii of Zr and Hf are same because of lanthanoid contraction

Answer Key:

a) La(OH)₃ is less basic than Lu(OH)₃

II. Short Answer Questions.

12th Chemistry

III. Long Answer Questions.

12th Chemistry

IV. Exercise.

12th Chemistry