Tag: the d-and f-block elements

Questions Related to the d-and f-block elements

Which of the following forms stable oxidation state?

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. Ce+ , Yb+

  2. Eu + , Tb+

  3. Lu+, Gd

  4. Pr5+ ,Nd2+

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Correct Option: A

Actinoids belongs to following type of elements:

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. s -block element

  2. d -block element

  3. f -block element

  4. p -block element

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Correct Option: C
Explanation:

The two rows that are generally placed underneath the main Periodic Table are called the lanthanide series and the actinide series.

These two rows are produced when electrons are being added to f orbitals.

Therefore, this block of elements are referred to as the "f block".

Which of the following elements is placed just after actinide series?

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. Rutherfordium

  2. Unnilpentium

  3. Unnilquadium

  4. Ununbium

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Correct Option: A,C
Explanation:

Actinide series starts with actinium (Z=89) and contains fourteen elements from thorium (Z=90) to lawrencium (Z=103). This is followed by Rutherfordium (Z=104). There Rutherfordium (Z=104) also known as Unnilquadium.

Hence, both a and c are the correct option.

The bonds generally formin compounds of Actinoids are:

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. convalent

  2. ionic

  3. coordinate covalent

  4. metallic

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Correct Option: B

Actinide element that exhibits highest oxidation state in its compounds (atomic numbers Th(90), U*, Np(93), Fm(100)

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. Th

  2. U*

  3. Np

  4. Fm

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Correct Option: B

Which one of the following elements shows maximum number of different oxidation states in its compounds ?

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. Eu

  2. La

  3. Gd

  4. Am

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Correct Option: D
Explanation:

Am shows +2, +3, +4, +5, +6, +7 oxidation states.

In the general electronic configuration,
$(n-2)f^{1-14} (n-1)d^{01} ns^2$ (where n = 7) the configuration will be of:

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. lanthenides

  2. actinides

  3. transition elements

  4. none

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Correct Option: B
Explanation:

General electronic configuration is given:
$(n -2) f^{1 -14} (n -1) d^{0 1} ns^2 ,where ( n =7 )$
$5f^{1 -14} 6d^{0 1 }ns^2$
The seventh period $(n=7)$ is similar to the sixth period with the successive filling up of the 7s, 5f, 6d and 7p orbitals and includes most of the man-made radioactive elements. This period will end at the element with atomic number 118 which would belong to the noble gas family. Filling up of the 5f orbitals after actinium $(Z=89)$ gives the 5f-inner transition series known as the Actinoid Series.

Most of the radio active elements are present in__________

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. Lanthanoids

  2. Actinoids

  3. Representative elements

  4. Second transition series

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Correct Option: B
Explanation:
The actinoids are radioactive elements and the earlier members have relatively long half-lives.

The most common and known element is Uranium, which is used as nuclear fuel when its converted into plutonium, through a nuclear reaction.

Option B is correct.

_________ form oxocations.

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. Lanthanides

  2. Actinides

  3. Noble gas

  4. Alkali metals

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Correct Option: B
Explanation:

Oxidations are the polyatomic cations contain one or more oxygen atoms. Actinides have a strong tendency towards the complex formation and form oxocations like oxides and hydroxides and are basic in nature.

The actinide contraction is due to:

chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

  1. perfect shielding of $5f$ election

  2. imperfect shielding of $4f$ election

  3. imperfect shielding of $5f$ electron

  4. perfect shielding of $4f$ election

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Correct Option: C
Explanation:

The actinide contraction is due to imperfect shielding of $5f$ electron. The valence shell electronic configuration of actinoids is $\displaystyle 5f^{1-14}6d^{0-1}7s^2$. With an increase in atomic number, the positive charge on the nucleus increases by $+1$, and one more electron enters in the same $5f$ subshell. There is imperfect shielding of one electron by another electron in the same $5f$ subshell. Due to this, the atomic and ionic radii show a gradual decrease with increase in atomic number.