AMATIR KANYA GURUKUL, KKR
UNIT TEST-II(2025-2026)
CLASS- XII
SUBJECT: CHEMISTRY (O43)
TIME: 1HOUR M.M:25
General Instructions:
i. This Question Paper contains 18 questions. All questions are compulsory.
ii. This Question paper is divided into 5 sections.
iii. Section A has 12 multiple choice questions (MCQs) carrying 0.5 mark each.
iv. Section B has 2 very short answer type questions, carrying 2 marks each.
v. Section C has 2 short answer type questions carrying 3 marks each.
vi. Section D consists of one case study based question of 4 marks.
vii. Section E consists of one long answer type question of 5 marks.
Section A:(12 * 0.5 = 6 marks)
CUET-based MCQs :
1. Which of the following ions is most stable?
a) Mn²⁺ b) Fe²⁺ c) Cu²⁺ d) Sc²⁺
2. Lanthanide contraction is caused due to:
a) Increase in nuclear charge b) Poor shielding of 4f electrons
c) Increase in atomic radius d) Increase in number of valence electrons
3. Which of the following complexes will have the highest crystal field splitting energy (Δ₀)?
a) [Fe(CN)₆]³⁻ b) [Fe(H₂O)₆]³⁺ c) [FeF₆]³⁻ d) [FeCl₆]³⁻
4. The oxidation state of iron in [Fe(CN)₆]⁴⁻ is:
a) +2 b) +3 c) 0 d) +4
5. Which of the following is not a property of transition metals?
a) Formation of coloured compounds b) High melting and boiling points
c) Formation of ionic hydrides d) Variable oxidation states
6. The coordination number of cobalt in [Co(NH₃)₄Cl₂]⁺ is:
a) 2 b) 4 c) 6 d) 5
CBSE-based MCQs :
7. Which element among the following shows +4 oxidation state most frequently?
a) Cr b) Mn c) Fe d) Co
8. Which f-block element is used in nuclear reactors?
a) Europium b) Uranium c) Lanthanum d) Cerium
9. In [Ni(CO)₄], the geometry of the complex is:
a) Square planar b) Tetrahedral c) Octahedral d) Trigonal bipyramidal
10. Which among the following ligands is bidentate?
a) CN⁻ b) H₂O c) C₂O₄²⁻ d) NH₃
Direction for Q.11and Q.12: In each of the following questions, a statement of Assertion is given and
a corresponding statement of Reason is given just below it. Of the statements, given below, mark the
correct answer as:
(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.
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11. Assertion (A): Transition metals form coloured compounds.
Reason (R): The colour of transition metal compounds is due to the presence of unpaired electrons and
d–d electronic transitions.
12. Assertion (A): In [Fe(CN)₆]³⁻ complex, Fe is in the +3 oxidation state and shows low spin
configuration.
Reason (R): CN⁻ is a strong field ligand which causes pairing of electrons in the d-orbitals of Fe³⁺.
Section B:[2*2=4 Marks]
13. Why do transition metals show variable oxidation states?
14. Give one difference between a double salt and a coordination compound.
OR
Why is the colour of K₄[Fe(CN)₆] different from that of K₃[Fe(CN)₆]?
Section C: [2*3=6 Marks]
15. Explain the following:
a) Actinoids show a greater range of oxidation states than lanthanoids.
b) Ce³⁺ is colourless while Ce⁴⁺ is coloured.
16. Write IUPAC names of the following complexes:
a) [Co(NH₃)₅Cl]Cl₂
b) [Pt(NH₃)₂Cl₂]
c) [Fe(C₂O₄)₃]³⁻
OR
Explain the Werner’s theory of coordination compounds with an example.
Section D: [1*4=4 Marks]
17. Read the passage and answer the following questions:
The d-block elements, also called transition elements, have a partially filled d-orbital in their atomic or
ionic states. These elements show variable oxidation states, form coloured ions, and have high melting
and boiling points. Among them, iron, cobalt, and nickel are ferromagnetic. The f-block elements are
known as inner transition elements, consisting of lanthanides and actinides. These elements are generally
radioactive, and their 4f or 5f orbitals are being filled. Lanthanides show a phenomenon called lanthanide
contraction.
Answer the following:
a) Why do d-block elements form coloured compounds?
b) What is lanthanide contraction?
c) Give one property that distinguishes actinoids from lanthanoids.
d) Which element among the d-block shows the highest number of oxidation states?
e) Why are transition metals good catalysts?
Section E: [1*5=5 Marks ]
18. (a) Explain crystal field theory for octahedral complexes. [2.5]
(b) Draw the crystal field splitting diagram and write the magnetic behaviour of [Fe(CN)₆]³⁻. [2.5]
OR
(a) What are interstitial compounds? How do transition metals form them? [2]
(b) Write two differences between lanthanoids and actinoids. [2]
(c) Why do transition metals form alloys? [1]
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