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Between PH3 (phosphine) and H2S (hydrogen sulfide), H2S is more acidic.

Acidity is typically measured by the ease with which a compound donates a proton (H⁺ ion) in solution. In both PH3 and H2S, the central atom (phosphorus in PH3 and sulfur in H2S) is bonded to three hydrogen atoms. However, the central atoms in these molecules differ in electronegativity.

Sulfur is more electronegative than phosphorus, meaning it has a stronger pull on the shared electrons in the hydrogen-sulfur bonds compared to phosphorus in the hydrogen-phosphorus bonds. This results in the hydrogen-sulfur bond being more polarized, with a partial positive charge on the hydrogen atom.

Consequently, the hydrogen atom in H2S is more easily ionizable (loses a proton) compared to the hydrogen atom in PH3. Therefore, H2S is considered a stronger acid compared to PH3.

The "lanthanoid contraction" refers to a phenomenon observed in the periodic table involving the contraction in atomic and ionic radii as you move across the lanthanide series (also known as the rare earth elements) from left to right.

This contraction occurs due to the poor shielding effect of f-electrons in the lanthanoid series. As electrons are added to the f-orbitals, they are not very effective at shielding the increasing nuclear charge from the outermost s- and p-electrons. As a result, the effective nuclear charge experienced by the outer electrons increases, leading to a contraction in the size of the atoms and ions as you move across the lanthanide series.

The lanthanoid contraction has significant consequences in various chemical properties, including ionization energy, atomic and ionic radii, and complex formation.

Transition elements exhibit variable oxidation states due to the presence of incompletely filled d orbitals in their atoms. These d orbitals can participate in bonding and can gain or lose electrons to form compounds with different oxidation states.

The number of oxidation states displayed by transition metals is often related to their electronic configurations. Transition metals have multiple incompletely filled d orbitals, which can easily lose or gain electrons to achieve a stable configuration. This flexibility allows them to exhibit a range of oxidation states.

For example, iron (Fe) can form compounds where it has an oxidation state of +2 or +3. In the +2 oxidation state, iron loses two electrons from its 4s orbital, while in the +3 oxidation state, it loses three electrons from both its 4s and 3d orbitals. Similarly, elements like chromium (Cr) can exhibit oxidation states ranging from -2 to +6.

The variability in oxidation states allows transition metals to form a wide variety of compounds with different properties and reactivities, making them essential in many chemical reactions and industrial processes.

The oxidation state of manganese (Mn) in its oxo-anion can be equal to its group number, which is +7. So, the formula of the oxo-anion would be MnO₄^(-), which is called permanganate ion.

Sure! Ionization isomerism is a type of structural isomerism where the composition of ions within a complex compound changes.

An example of ionization isomerism is seen in the coordination compound [Co(NH3)5SO4]Br and [Co(NH3)5Br]SO4.

In the first compound, [Co(NH3)5SO4]Br, the sulfate ion (SO4) is coordinated to the cobalt ion (Co) while the bromide ion (Br) is outside the coordination sphere.

In the second compound, [Co(NH3)5Br]SO4, the bromide ion (Br) is coordinated to the cobalt ion (Co) while the sulfate ion (SO4) is outside the coordination sphere.

So, in these two compounds, the ions are arranged differently around the central cobalt ion, leading to ionization isomerism.

The complex Co(NH3)5(NO2)2 exhibits two types of isomerism:

1. Coordination Isomerism: Coordination isomers occur when the ligands in a complex exchange places with anionic or neutral ligands outside the coordination sphere. In this complex, NO2 and NO3 can interchange positions, leading to the formation of coordination isomers.

2. Ionization Isomerism: Ionization isomers arise when there's a difference in the location of a ligand within a complex or between an ion and a molecule. In this case, the NO3^- ions in the coordination sphere can exchange positions with the NO3^- ions outside the coordination sphere.

When undecomposed silver bromide (AgBr) is washed with hypo solution (sodium thiosulfate) in photography, it forms a complex ion known as the tetrathionate complex, [Ag(S2O3)2]3-. This complex ion helps in removing the unexposed silver bromide from the photographic film during the fixing process, leaving behind the developed silver image.