Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

They are chemically very reactive

They have high melting points in comparison to pure metals

They retain metallic conductivity

They are chemically very reactive

A transition metal exists in its highest oxidation state. It is expected to behave as:

A central metal in a coordination compound

All Cu (II) halidesknown except iodide. The reason for this is that:

Cu2+ (aq.) has much more negative hydration enthalpy

The actinoid exhibit more number of oxidation states in general than the lanthanoids. This is because:

The 5f orbitals extend farther from the nucleus than the 4f orbitals

The 5f orbitals are more buried than the 4f orbitals

There is a similarity between the 4f and 5f orbitals in their angular part of the wave function

The actinoids are more reactive than the lanthanoids

The D And F Block Elements

1.

Which of the following oxidation state is common for all lanthanoids?
- A.
  
  + 2
- B.
  
  + 3
- C.
  
  + 4
- D.
  
  + 5
Correct Answer
B. + 3

Explanation
The common oxidation state for all lanthanoids is +3. Lanthanoids are a group of elements in the periodic table that have similar chemical properties. They have a filled 4f electron shell, and when they form compounds, they typically lose three electrons to achieve a stable configuration. This results in an oxidation state of +3 for all lanthanoids.

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2.

Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?
- A.
  
  They have high melting points in comparison to pure metals
- B.
  
  They are very hard
- C.
  
  They retain metallic conductivity
- D.
  
  They are chemically very reactive
Correct Answer
D. They are chemically very reactive

Explanation
Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. They exhibit several characteristic properties such as high melting points, hardness, and retention of metallic conductivity. However, interstitial compounds are not chemically very reactive. This is because the trapped atoms do not easily participate in chemical reactions due to their tightly bound positions within the crystal lattice.

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3.

When acidified K₂Cr₂O₇ solution is added to Sn²⁺ salts, then Sn²⁺ changes to:
- A.
  
  Sn
- B.
  
  Sn³⁺
- C.
  
  Sn^4+v
- D.
  
  Sn⁺
Correct Answer
C. Sn^4+v

Explanation
When acidified K2Cr2O7 solution is added to Sn2+ salts, the Sn2+ ions are oxidized to Sn4+ ions. This is because K2Cr2O7 is a strong oxidizing agent and can transfer oxygen atoms to Sn2+ ions, resulting in the formation of Sn4+ ions.

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4.

Metallic radii of some transition elements are given below. Which of these elements will have highest density?
- A.
  
  Fe
- B.
  
  Ni
- C.
  
  Co
- D.
  
  Cu
Correct Answer
D. Cu

Explanation
Copper (Cu) will have the highest density among the given transition elements. This is because density is directly proportional to atomic mass and inversely proportional to atomic radius. Cu has the highest atomic mass among Fe, Ni, Co, and Cu. Additionally, Cu has a smaller atomic radius compared to the other elements, which further contributes to its higher density.

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5.

A student accidently added conc. H₂SO₄ to potassium permagnate and it exploded due to the formation of an explosive which is:
- A.
  
  MnO
- B.
  
  Mn₂O₃
- C.
  
  Mn₂O₅
- D.
  
  Mn₂O₇
Correct Answer
D. Mn₂O₇

Explanation
When concentrated sulfuric acid (H2SO4) is added to potassium permanganate (KMnO4), it reacts to form manganese heptoxide (Mn2O7). Manganese heptoxide is a highly explosive compound, which explains why the mixture exploded.

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6.

KMnO₄ acts an oxidizing agent in alkaline medium. When alkaline KMnO₄ is treated with KI, iodide ion is oxidesed to:
- A.
- B.
- C.
- D.
Correct Answer
C.
7.

A transition metal exists in its highest oxidation state. It is expected to behave as:
- A.
  
  A chelating agent
- B.
  
  A central metal in a coordination compound
- C.
  
  An oxidizing agent
- D.
  
  A reducing agent
Correct Answer
C. An oxidizing agent

Explanation
A transition metal in its highest oxidation state has a high affinity for electrons and tends to gain electrons from other substances. This makes it an excellent oxidizing agent as it can easily accept electrons and cause other substances to lose electrons, resulting in oxidation reactions.

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8.

For successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?
- A.
  
  Cr > Mn > Co > Fe
- B.
  
  Mn > Fe > Cr > Co
- C.
  
  Fe > Mn > Co > Cr
- D.
  
  Co > Mn > Fe > Cr
Correct Answer
B. Mn > Fe > Cr > Co

Explanation
The stability of the +2 oxidation state for the successive transition elements follows the order Mn > Fe > Cr > Co. This means that Mn has the highest stability for the +2 oxidation state, followed by Fe, Cr, and then Co.

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9.

The colour of light absorbed by an aqueous solution of CuSO₄ is
- A.
  
  Orange-red
- B.
  
  Blue-green
- C.
  
  Yellow
- D.
  
  Violet
Correct Answer
A. Orange-red

Explanation
An aqueous solution of CuSO4 absorbs light in the orange-red region of the electromagnetic spectrum. This is because when light passes through the solution, the Cu2+ ions present in the solution absorb photons of light that have energies corresponding to the orange-red wavelength range. This absorption occurs due to the electronic transitions within the Cu2+ ions. As a result, the solution appears orange-red in color.

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10.

When hydrogen peroxide is added to acidified potassium dichromate, a blue colour is produced due to the formation of:
- A.
- B.
- C.
- D.
Correct Answer
C.

Explanation
When hydrogen peroxide is added to acidified potassium dichromate, a blue color is produced due to the formation of chromium(III) ions. The reaction involves the reduction of the orange dichromate ions (Cr2O7^2-) to green chromium(III) ions (Cr^3+). This reduction reaction is facilitated by the oxidizing agent hydrogen peroxide. The blue color observed is due to the presence of the chromium(III) ions in solution.

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11.

Lanthanoid contraction is observed in:
- A.
  
  Gd
- B.
  
  At
- C.
  
  Xe
- D.
  
  Ac
Correct Answer
A. Gd

Explanation
Lanthanoid contraction refers to the decrease in atomic and ionic radii of elements in the lanthanoid series as the atomic number increases. Gd (Gadolinium) is an element in the lanthanoid series, and therefore, it exhibits the phenomenon of lanthanoid contraction.

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12.

Ammonium dichromate is used in fireworks. The green coloured powder blown in the air is:
- A.
  
  CrO₃
- B.
  
  Cr₂O₃
- C.
  
  Cr
- D.
  
  CrO (O₂
Correct Answer
B. Cr₂O₃

Explanation
Ammonium dichromate is used in fireworks to produce a green color. The correct answer, Cr2O3, is chromium(III) oxide, which is a green-colored powder.

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13.

Which of the following lanthanoid ion is paramagnetic?
- A.
  
  Ce⁴⁺
- B.
  
  Option 2Yb²⁺
- C.
  
  Lu³⁺
- D.
  
  4Eu²⁺
Correct Answer
D. 4Eu²⁺

Explanation
Eu2+ is paramagnetic because it has an unpaired electron. Paramagnetic substances are attracted to a magnetic field due to the presence of unpaired electrons, which creates a net magnetic moment. Ce4+, Yb2+, and Lu3+ do not have unpaired electrons and are therefore diamagnetic.

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14.

All Cu (II) halidesknown except iodide. The reason for this is that:
- A.
  
  Iodide ion is a bulky ion
- B.
  
  Cu²⁺ oxidizes iodide to iodine
- C.
  
  Cu²⁺ (aq.) has much more negative hydration enthalpy
- D.
  
  Cu²⁺ion has smaller size
Correct Answer
B. Cu²⁺ oxidizes iodide to iodine

Explanation
Cu2+ oxidizes iodide to iodine because Cu2+ is a strong oxidizing agent. It has a high tendency to gain electrons and undergo reduction reactions. In the presence of iodide ions, Cu2+ can easily accept electrons from iodide and convert it into iodine. This reaction is favored because iodine has a lower oxidation state compared to iodide. Therefore, Cu2+ oxidizes iodide to iodine.

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15.

The actinoid exhibit more number of oxidation states in general than the lanthanoids. This is because:
- A.
  
  The 5f orbitals extend farther from the nucleus than the 4f orbitals
- B.
  
  The 5f orbitals are more buried than the 4f orbitals
- C.
  
  There is a similarity between the 4f and 5f orbitals in their angular part of the wave function
- D.
  
  The actinoids are more reactive than the lanthanoids
Correct Answer
A. The 5f orbitals extend farther from the nucleus than the 4f orbitals

Explanation
The answer is the 5f orbitals extend farther from the nucleus than the 4f orbitals. This is because the distance of an electron from the nucleus determines its energy level and reactivity. The farther an electron is from the nucleus, the higher its energy level and the more easily it can participate in chemical reactions. Since the actinoids have electrons in the 5f orbitals, which are farther from the nucleus than the 4f orbitals of the lanthanoids, they can exhibit a greater number of oxidation states and are therefore more reactive.

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The D And F Block Elements

Which of the following oxidation state is common for all lanthanoids?

Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

When acidified K2Cr2O7 solution is added to Sn2+ salts, then Sn2+ changes to:

Metallic radii of some transition elements are given below. Which of these elements will have highest density?

A student accidently added conc. H2SO4 to potassium permagnate and it exploded due to the formation of an explosive which is:

KMnO4 acts an oxidizing agent in alkaline medium. When alkaline KMnO4 is treated with KI, iodide ion is oxidesed to:

A transition metal exists in its highest oxidation state. It is expected to behave as:

For successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?

The colour of light absorbed by an aqueous solution of CuSO4 is

When hydrogen peroxide is added to acidified potassium dichromate, a blue colour is produced due to the formation of:

Lanthanoid contraction is observed in:

Ammonium dichromate is used in fireworks. The green coloured powder blown in the air is:

Which of the following lanthanoid ion is paramagnetic?

All Cu (II) halidesknown except iodide. The reason for this is that:

The actinoid exhibit more number of oxidation states in general than the lanthanoids. This is because:

When acidified K₂Cr₂O₇ solution is added to Sn²⁺ salts, then Sn²⁺ changes to:

A student accidently added conc. H₂SO₄ to potassium permagnate and it exploded due to the formation of an explosive which is:

KMnO₄ acts an oxidizing agent in alkaline medium. When alkaline KMnO₄ is treated with KI, iodide ion is oxidesed to:

The colour of light absorbed by an aqueous solution of CuSO₄ is