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The d block elements are placed in the group 3-12 and F block element with 4f and 5f orbital filled progressively. General electronic configuration of d block elements is (n-1) d 1-10 ns 1-2. The General Electronic configuration of f- block elements is (n-2) f 1-14 (n-1) d1 ns2 . They are also known as transition elements because they exhibit multiple oxidation states due to the d-d transition which is possible by the availability of vacant d orbitals in these elements.
They have variable Oxidation States as well as are good catalysts because they provide a large surface area for the absorption of reaction. They show variable oxidation states to form intermediate with reactants easily. They are mostly lanthanoids and show lanthanoid contraction. Since differentiating electrons enter in an anti-penultimate f subshell. Therefore, these elements are also called inner transition elements
Ques 1: From the periodic table which block elements are known as Transition Elements?
- f- block elements
- s- block elements
- d- block elements
- p- block elements
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Answer: c) d – block elements
Explanation: The d Block Elements lie between s and p block so some of their properties resemble with p and some with s block. Due to this transition behavior, they are known as Transition Elements.
By the absorption of light excitation of an electron occurs from 1d orbital to another. Due to this d-d transition, they are known as Transition Elements.
But the elements that have partially filled d-subshell in neutral atoms or in one of their Oxidation states are transition elements from d block.
Ques 2: Which of the following forms compounds of the highest oxidation state with transition elements?
- Oxygen (O)
- Fluorine(F)
- Both a and b
- None of the above
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Answer: c) Both a and b
Explanation: As the reduction potential of Oxygen and fluorine is high so they are good oxidizing agents. Thus, it forms the compound with the highest oxidation State with transition elements.
Ques 3: Choose the correct general electronic configuration of d Block Elements valence shell.
- (n-1) d 1-10 ns 1-2
- b. (n-1) d 1-5 ns 2
- (n-1) d10 ns 2
- n d 1-10 (n-1) s 1-2
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Answer: (a) (n-1) d 1-10 ns 1-2
Explanation:The d-block element's general electronic configuration is (n-1) d 1-10 ns 1-2 The element whose outermost shells are incomplete and falling off the last electron of these elements in the penultimate d- subshell. Since valence electrons are the same along the period.
Ques 4:Select the diamagnetic ion from the given below:
- Ni2+
- Cu2+
- Zn2+
- Co2+
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Answer: c) Zn2+
Explanation: The elements which have no unpaired electrons are called diamagnetic. As Zinc does not have unpaired electrons, thus, it is diamagnetic. So , Zn2+ ions are diamagnetic.
Ques 5:From the given below select the pair which has same ionic size:
- Zr4+, Hf4+
- Zn2+, Hf4+
- Fe2+, Ni2+
- Zr4+, Ti4+
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Answer: a) Zr4+, Hf4+
Explanation: When we move from atomic number 58 to 71 the atomic size/ ionic radii of trivalent ions decrease. This is called Lanthanoid contraction. Due to Lanthanoid contraction Zr4+, Hf4+ have similar size.
Ques 6: When SO2 gas is passed through acidified K2Cr2O7 solution, the solution turns green due to the formation of:
- Cr2(SO4)3
- CrO42-
- Cr2(SO3)3
- CrSO4
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Answer: a)Cr2(SO4)3
Explanation: Sulphur dioxide reacts with acidified potassium dichromate to form chromium sulphate, potassium sulphate and water. Potassium dichromate turns a golden yellow solution of potassium dichromate green.
Ques 7: Among the following which one is green vitriol?
- FeSO4.7H2O
- CuSO4. 5H2O
- CaSO4. 2H2O
- None of these
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Answer: (a) FeSO4. 7H2O
Explanation: Iron sulphate or ferrous sulphate is known as green vitriol. The blue color heptahydrate dissolves in the water to form an aqua complex with octahedral geometry. It is used in medical purposes for treating iron deficiency as it is paramagnetic in nature.
Ques 8: The electronic configuration of Cu (II) is 3d9 whereas that of Cu(I) is 3d10. Which of the following is correct? [NCERT Exemplar]
- Cu (II) is more stable
- Cu (II) is less stable
- Cu(I) and Cu (II) are equally stable
- Stability of Cu(I) and Cu (II) depends on nature of copper salts
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Answer: a) Cu (II) is more stable
Explanation: The hydration energy or enthalpy is determined when an ion is bonded with the water molecules. So, when the hydration energy is high then the stability will be more. Hence, Cu (II) is more stable as hydration energy is high.
Ques 9: Element which shows multiple oxidation States. As well as in aqueous solution medium their ions are usually color is known as:
- Non-Metal
- Transition elements
- Metalloids
- Gases
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Answer: b) Transition elements
Explanation: These elements are known as transition elements. They generally exhibit multiple oxidation states due to the d-d transition which is possible by the availability of vacant d orbitals in these elements. The d-d transition occurs between different molecular orbitals (MO) and is an electronic transition which is mostly metallic in character.
Ques 10: Which of the following is a Lanthanoid?
- Sodium
- Potassium
- Plutonium
- Lanthanum
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Answer: d) Lanthanum
Explanation: Elements after lanthanum from atomic number 58 to 71 are called lanthanides. They are also called rare Earth elements as they are rarely found in the earth crust. Since differentiating electrons enter in an anti-penultimate f subshell. Therefore, they are also called inner transition elements.
Ques 11: Choose the correct general electronic configuration of f Block Elements valence shell.
- (n-2) f 1-14 (n-1) d1 ns2
- b. (n-1) f 1-14 nd1 ns2
- (n-1) f10 ns 2
- n f1-10 (n-1) d 1-2
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Answer: (a) (n-2) f 1-14 (n-1) d1 ns2
Explanation:Since differentiating electron enters in anti-penultimate f subshell, there electronic configuration is (n-2) f 1-14 (n-1) d1 ns2
Ques 12: Mostly chromates are of which color:
- yellow
- orange
- green
- purple
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Answer: a) yellow
Explanation: Due to charge transfer transition in the visible light region that is transfer of an electron from d localized molecular orbital to oxygen delocalized molecular orbital in Chromium.
Ques 13: The transition elements exhibit which of the following behaviors:
- Magnetic behavior
- Catalytic behavior
- Solid compound formation behavior
- All of the above
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Answer: d) All of the above
Explanation: The transition elements mostly have unpaired electrons in the d subshell. So, they show paramagnetic behavior. Hence, magnetic in nature.
They are good catalysts because they provide a large surface area for the absorption of reaction. They show variable oxidation states to form intermediate with reactants easily.
They form color compounds due to the presence of unpaired electrons. Due to polarisation as polarisation is directly proportional to the intensity. Also, the formation of their oxysalts are colorful due to charge transfer spectrum.
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