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All questions of D and F - Block Elements for NEET Exam

Can you explain the answer of this question below:
Which one of the following is a diamagnetic ion?
  • A:
    CO2+
  • B:
    Cu2+
  • C:
    Mn2+
  • D:
    Sc3+
The answer is d.

Co+2 = [Ar] 3d7
Cu2+ = [Ar] 3d9
Mn+2 = [Ar] 3d5
Sc+3 = [Ar]
We can see that only Sc+3  has no unpaired electron, so it is a diamagnetic ion.

Which one of the following exists in the oxidation state other than +3?
  • a)
    B
  • b)
    Al
  • c)
    Ce
  • d)
    Ga
Correct answer is option 'C'. Can you explain this answer?

Vivek Rana answered
The correct answer is option C
Ce exist in the oxidation state other than +3 .
 
(a) B - Boron has +1 and +3 oxidation state.
(b) Al - Aluminium has +1,+2 and +3 oxidation state.
(c) Ce - Cerium has +3 and +4 oxidation state.
(d) Ga - Gallium has +1 and +3 oxidation state.
Cerium (Ce) have [Xe] 4f²6s² electronic configuration.

Which form of silver is colourless?
  • a)
    Ag2+
  • b)
    Ag
  • c)
    Ag3+
  • d)
    Ag+
Correct answer is option 'D'. Can you explain this answer?

Om Desai answered
ilver in the form of Ag+ is colourless. For transition metal ions to exhibit color, their metal ions must have incompletely filled (n-1)d orbitals.
Ag+ =4d10,5s0
Ag+ has completely filled d orbitals hence is colourless.

Which ion will show more paramagnetic behaviour ?
  • a)
    Cu+
  • b)
    Fe2+
  • c)
    Ag+
  • d)
    Fe3+
Correct answer is option 'D'. Can you explain this answer?

Lavanya Menon answered
Since the configuration of Fe3+ ion is (argon ) 3d5,which contains maximum number of unpaired electrons, hence more will be paramagnetic behavior.

 Which among the following is colourless?
  • a)
    Sc2+
  • b)
    Zn2+
  • c)
    Ti3+
  • d)
    V3+
Correct answer is option 'B'. Can you explain this answer?

Krishna Iyer answered
Zn2+ has completely filled d-orbitals and there are no vacant d-orbitals for the transition of electrons, hence it is colourless.

The first ionization energy of the d-block elements are?
  • a)
    Lesser than p-block elements
  • b)
    Between s and p-block elements
  • c)
    Lesser than s-block elements
  • d)
    Higher than p-block elements
Correct answer is option 'B'. Can you explain this answer?

Rahul Bansal answered
The first ionization energy of the d-block elements are between s and p-block elements. Thus they are more electropositive than p-block elements and less electropositive than s-block elements.

Which of the following group of elements are not regarded as transition elements?
  • a)
    Sc,Y,La
  • b)
    Cu, Ag, Au
  • c)
    Zn, Cd, Hg
  • d)
    Cr ,Mo,W
Correct answer is option 'C'. Can you explain this answer?

Neha Sharma answered
Zn, Cd & Hg because the d-orbital of these elements are completely filled. So, they don't show the characteristics of transition elements (i.e. the d-orbital of transition elements is incomplete.

 In which of the following oxidation states La achieve the noble gas configuration?
  • a)
    +7
  • b)
    +3
  • c)
    +5
  • d)
    +2
Correct answer is option 'B'. Can you explain this answer?

Shail Chawla answered
La stands for Lanthanum, which is a member of the lanthanide series of elements in the periodic table. It has an atomic number of 57 and an electronic configuration of [Xe]5d1 6s2.

Achieving Noble Gas Configuration
To achieve a noble gas configuration, an element must have its outermost shell filled with electrons. The noble gases are stable because they have a filled outermost shell. Lanthanum can achieve this configuration by losing three electrons from its outermost shell.

Oxidation States
The oxidation state of an element is the charge that it carries when it forms a compound or ion. Lanthanum can form compounds in various oxidation states, including +2, +3, and +4.

In order to determine in which oxidation state La achieves noble gas configuration, we need to look at its electron configuration and determine how many electrons it needs to lose to achieve a filled outermost shell.

La3+ (Oxidation State of +3)
When Lanthanum loses three electrons, it forms a +3 ion (La3+). In this oxidation state, La has a noble gas configuration of [Xe]. Therefore, option B is the correct answer.

Other Oxidation States
Lanthanum can also form compounds in other oxidation states, but they do not achieve a noble gas configuration. For example, in the +2 oxidation state, La has an electron configuration of [Xe]5d1, which is not a filled outermost shell.

Conclusion
In conclusion, Lanthanum achieves noble gas configuration in the +3 oxidation state by losing three electrons and forming a La3+ ion.

 The inner transition elements are the elements in which the added electrons go to:
  • a)
    (n-1)d-orbitals
  • b)
    (n-1)d-orbitals and (n-1)f-orbitals
  • c)
    (n-1)d-orbitals and ns orbitals
  • d)
    (n-2)f-orbitals
Correct answer is option 'D'. Can you explain this answer?

Rohit Shah answered
 Lanthanides and actinides are called inner transition elements because they are a group of elements that are shown as the bottom two rows of the periodic table. ... Lanthanides and actinides belong to the f-block elements, which means that they have filled up their f-orbitals with electrons.

Number of electrons with l = 2 and s = 1/2 in zinc atom are
    Correct answer is '5'. Can you explain this answer?

    Krishna Iyer answered
    l = 2 means d-subshell. Zinc has 10 electrons ind-subshell in which 5 electrons are + 1/2 spin and 5 electrons are - 1/2.

    What is the most common oxidation state for actinoids?
    • a)
      +3
    • b)
      +7
    • c)
      +2
    • d)
      +5
    Correct answer is option 'A'. Can you explain this answer?

    Mamali . answered
    Unlike lanthanides which show the +3, oxidation States,actinides show a variety of Oxidation State from +3to+6.However+3&+4 are the principal Oxidation State.The+3 Oxidation state is the most stable in AC and all the other elements of the series.Thats it.

    The elements which lie between s and p block elements in the long form periodic table are called as:
    • a)
      Actinides
    • b)
      d-block elements
    • c)
      Lanthanides
    • d)
      Electropositive elements
    Correct answer is option 'B'. Can you explain this answer?

    Harsh Desai answered
    D-block elements

    The long form periodic table consists of four blocks: s, p, d, and f. The s and p blocks are located on the left and right sides of the periodic table, respectively. The d-block elements are located in the middle of the periodic table, between the s and p blocks. These elements are also known as transition elements.

    Explanation:

    The d-block elements are characterized by the presence of partially filled d-orbitals in their valence shells. These elements are often referred to as transition elements because they exhibit a transition between the highly reactive s-block elements and the relatively inert p-block elements. The d-block elements are known for their unique chemical and physical properties, such as their ability to form complex ions and their high melting and boiling points.

    Examples of d-block elements include titanium, iron, copper, and zinc. These elements are widely used in industry and technology due to their unique properties, such as their strength, durability, and conductivity.

    In summary, the elements which lie between s and p block elements in the long form periodic table are called d-block elements or transition elements. These elements exhibit unique chemical and physical properties and are widely used in industry and technology.

     Melting point of d block elements across a period:
    • a)
      Increases from left to right
    • b)
      Deceases from left to right
    • c)
      Increases to a maximum at d5 and then decreases with increase of atomic number.
    • d)
      Does not change on moving from left to right.
    Correct answer is option 'C'. Can you explain this answer?

    Jayant Mishra answered
    The melting and boiling points first increase, reaches maximum and then steadily decrease across any transition series. ... The low melting points of Zn, Cd, and Hg are due to the absence of unpaired d-electrons in their atoms and thus low metallic bonding.

    Which one is of the following is the lightest transition element?
    • a)
      Ti 
    • b)
      Sc 
    • c)
      Fe 
    • d)
      Hg
    Correct answer is option 'B'. Can you explain this answer?

    T.ttttt answered
    Scandium (Sc) is the lightest transition element. It is the first element in the 3d transition series. Among the transition elements, Sc has the lowest density.

     Which of the following group contain mostly radioactive elements ?
    • a)
      Lanthanoids
    • b)
      3 d transition series
    • c)
      4 d transition series
    • d)
      Actinoids
    Correct answer is option 'D'. Can you explain this answer?

    Parth Sharma answered
    The actinoids are said to be most radioactive metals because in this group all the metals have very oxidation number and are very rare metals found on earth and it has all the elements radioactive in its group and it has most radioactive metal uranium in it's group.

     Mischmetal is an alloy of:
      • a)
        Lanthanoid metal and Iron
      • b)
        Actinoid metal and Iron
      • c)
        Manganese, nickel and iron
      • d)
        Zinc ,cobalt and iron
      Correct answer is option 'A'. Can you explain this answer?

      Snehal Iyer answered
      Explanation:

      Mischmetal is an alloy of Lanthanoid Metal and Iron. It is a rare earth alloy, which is primarily used in the production of alloy steels, stainless steels, and other high-performance alloys.

      Composition:

      Mischmetal typically contains 50-55% cerium, 20-25% lanthanum, and small amounts of other rare earth metals such as neodymium, praseodymium, and gadolinium. The remaining portion of the alloy is typically iron.

      Properties:

      Mischmetal has a number of unique properties that make it an attractive alloy for use in a variety of applications. These properties include:

      - High heat resistance
      - High strength and durability
      - Corrosion resistance
      - Good machinability

      Applications:

      Mischmetal is primarily used in the production of alloy steels, stainless steels, and other high-performance alloys. It is also used in the production of magnesium alloys, which are used in a variety of applications, including aerospace, automotive, and sporting goods.

      Some other applications of Mischmetal are:

      - In the production of lighter flints
      - As a pyrophoric material for the ignition of torches and lighters
      - In the production of certain types of electrodes for welding and cutting
      - In the production of certain types of batteries

      Conclusion:

      In conclusion, Mischmetal is an alloy of lanthanoid metal and iron, primarily used in the production of alloy steels, stainless steels, and other high-performance alloys. It has a number of unique properties that make it an attractive alloy for use in a variety of applications.

      Transition metals with highest melting point is
      • a)
        Cr
      • b)
        W
      • c)
        Hg
      • d)
        Sc
      Correct answer is option 'B'. Can you explain this answer?

      W belongs to 5d series and also it have lot of unpaired electrons thus it forms strong metallic bonding.

      During the process of electrolytic refining of copper, some metals present as impurity settle as ‘anode mud’ These are
      • a)
        Sn and Ag
      • b)
        Pb and Zn
      • c)
        Ag and Au
      • d)
        Fe and Ni
      Correct answer is option 'C'. Can you explain this answer?

      Hansa Sharma answered
      The correct answer is option C
      In Electrolytic refining, the impure metal is made to act as an anode. A strip of the same metal in pure form is used as a cathode. 
      They are put in a suitable electrolytic bath containing a soluble salt of the same metal. 
      The more basic metal remains in the solution and the less basic ones go to the anode mud.
      Copper is refined using an electrolytic method.
      Impurities from the blister copper deposit as anode mud which contains antimony, selenium, tellurium, silver, gold, and platinum; recovery of these elements may meet the cost of refining.

      Which one of the following is a diamagnetic ion?
      • a)
        CO2+
      • b)
        Cu2+
      • c)
        Mn2+
      • d)
        Sc3+
      Correct answer is option 'D'. Can you explain this answer?

      Ameya Pillai answered
      Co2+ (Z = 27) : [Ar]183d7 (3 unpaired electrons)
      Cu2+ (Z = 29) : [Ar]183d9 (1 unpaired electrons)
      Mn2+ (Z = 25): [Ar]183d5 (5 unpaired electrons)
      Sc3+ (Z = 21): [Ar]183d0 (No unpaired electron)
      Sc3+ with no unpaired electron will be diamagnetic

      In which of the following oxidation state Cerium achieves the noble gas configuration?
      • a)
        +5
      • b)
        +2
      • c)
        +7
      • d)
        +4
      Correct answer is option 'D'. Can you explain this answer?

      Mamali . answered
      The reason for this behaviour is a result of the stability of half filled, empty or fulfilled F orbitals that these elements achieve in these Oxidation State.Thats it.

      Which has lowest and highest first ionisation enthalpy in 3d series?
      • a)
        Sc and Zn
      • b)
        Zn and Sc
      • c)
        Cu and Zn
      • d)
        Cr and Zn
      Correct answer is option 'A'. Can you explain this answer?

      Losing one electron gives Sc noble gas configuration (Ar). While Zn has d10 s2 configuration so it won't give its electron easily. So, it has high ionization enthalpy.

      The catalytic activity of transition metals and their compounds is ascribed mainly to :[2012 M]
      • a)
        their magnetic behaviour
      • b)
        their unfilled d-orbitals
      • c)
        their ability to adopt variable oxidation state
      • d)
        their chemical reactivity
      Correct answer is option 'C'. Can you explain this answer?

      The transition metals and their compounds are used as catalysts. Because of the variable oxidation states, due to this, they easily absorb and re-emit wide range of energy to provide the necessary activation energy.

      The pair of ions that have same electronic configuration
      • a)
        Fe2+ and Mn2+
      • b)
        Fe2+ and Co3+
      • c)
        Fe3+ and Co3+
      • d)
        V2+ and Cr3+
      Correct answer is option 'B,D'. Can you explain this answer?

      Saikat Dey answered
      You simply count the electron number, though , co is present just after fe, so from this logic you count the electron number is same in fe2+ and co3+,(just think) simultaneously v2+, cr3+ electron number is same, in mathematical, fe 2+ electron number is 26-2=24,, and co 3+,electron number is 27-3=24,so simultaneously v2+, and cr 3+ has same number of electron,

       Which of the following statement is true?
      • a)
        Actinoid contraction is smaller than lanthanoid contraction.
      • b)
        There is no actinoid contraction observed.
      • c)
        Actinoid contraction is greater than lanthanoid contraction.
      • d)
        Actinoid contraction is equally same as lanthanoid contraction.
      Correct answer is option 'C'. Can you explain this answer?

      Anshika Menon answered
      Actinoid Contraction and Lanthanoid Contraction

      Actinoid contraction and lanthanoid contraction are terms used to describe the decrease in atomic and ionic radii of the elements in the actinide and lanthanide series, respectively.

      Actinoid Contraction

      - Actinoid contraction refers to the decrease in atomic and ionic radii of the elements in the actinide series.
      - It is caused by the imperfect shielding of the 5f electrons by the 6s and 6p electrons.
      - The 5f electrons are located closer to the nucleus and experience a greater effective nuclear charge, which leads to a smaller atomic and ionic radius.
      - Actinoid contraction is observed in the actinide series from thorium (Z=90) to lawrencium (Z=103).

      Lanthanoid Contraction

      - Lanthanoid contraction refers to the decrease in atomic and ionic radii of the elements in the lanthanide series.
      - It is caused by the imperfect shielding of the 4f electrons by the 5s, 5p, and 6s electrons.
      - The 4f electrons are located closer to the nucleus and experience a greater effective nuclear charge, which leads to a smaller atomic and ionic radius.
      - Lanthanoid contraction is observed in the lanthanide series from cerium (Z=58) to lutetium (Z=71).

      Comparison of Actinoid Contraction and Lanthanoid Contraction

      - Actinoid contraction is greater than lanthanoid contraction.
      - The 5f electrons in the actinide series experience a greater effective nuclear charge than the 4f electrons in the lanthanide series, which leads to a greater decrease in atomic and ionic radii.
      - Actinoid contraction is also observed over a smaller range of elements than lanthanoid contraction.

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