chemistry QUIZ 1

The ion which has the highest magnetic moment is…

• Cr⁺⁴

• V⁺²

• Fe⁺³

• Sc⁺³

Answer explanation

The ion Fe+3 has the highest magnetic moment because it has an unpaired electron in its d orbital. This unpaired electron allows Fe+3 to have a higher magnetic moment compared to the other ions listed. The other ions do not have unpaired electrons in their d orbitals, so their magnetic moments are lower.

1. If you have two solutions, one of them contains V³⁺ ions and the other contains Zn²⁺ ions. Which of those solutions is colorless? [ V³⁺- Zn²⁺]

• Zn²⁺, all of its d-electrons are unpaired

• 
  V³⁺ ,all of its d-electrons are paired

• 
  V³⁺ ,all of its d-electrons are unpaired

• Zn²⁺, all of its d-electrons are paired

Answer explanation

The correct answer is Zn2+, all of its d-electrons are paired. This is because when all of the d-electrons in an ion are paired, it results in a colorless solution. In contrast, when the d-electrons are unpaired, it can lead to the absorption of certain wavelengths of light, causing the solution to appear colored. In the case of V3+ ions, all of its d-electrons are unpaired, which can result in a colored solution. However, in Zn2+ ions, all of its d-electrons are paired, leading to a colorless solution.

Choose a word to illustrate the following phrase: Two elements of the first transition series each having only one oxidation state.

• 
  Scandium and zinc

• Copper and chromium

• Scandium and copper

• Zinc and nickel

Answer explanation

Scandium and zinc are the correct answer because they are the only two elements in the first transition series that have only one oxidation state. Scandium has an oxidation state of +3, while zinc has an oxidation state of +2. The other options, copper, nickel, and chromium, all have multiple oxidation states.

The compound FeCl₂ is…

• Paramagnetic and colorless

• Diamagnetic and colored

• 
  Paramagnetic and colored

• Diamagnetic and colorless

Answer explanation

FeCl2 is paramagnetic because it contains unpaired electrons. Paramagnetic substances are attracted to a magnetic field due to the presence of unpaired electrons. It is also colored because the presence of unpaired electrons allows for absorption and emission of specific wavelengths of light, resulting in a visible color.

An element belongs to the first transition series, it’s magnetic moment in X₂O₃ compound equals 3, deduce the atomic number of this element

• 
  26

• 24

• 22

• 
  21

Answer explanation

The atomic number of an element determines the number of protons in its nucleus. In the first transition series, the elements have atomic numbers ranging from 21 to 30. The magnetic moment in X2O3 compound equals 3 indicates that the element has three unpaired electrons. Based on the electron configuration of transition metals, an element with three unpaired electrons would have an atomic number of 24, which corresponds to chromium (Cr). Therefore, the correct answer is 24.

• 
  Determine the ions which can’t be produced by normal chemical reactions from the following: 1) Sc²⁺   2)Mn⁴⁺    3) Co²⁺    4)Zn+

• 2 and 3

• 1 and 2

• 1 and 4

• 3 and 4

Answer explanation

The ions that cannot be produced by normal chemical reactions are Sc2+ and Zn+. Scandium (Sc) typically forms a +3 ion, not a +2 ion. Zinc (Zn) typically forms a +2 ion, not a +1 ion. Therefore, Sc2+ and Zn+ cannot be produced by normal chemical reactions.