Group 16 Elements

To solve this question, let's analyze each statement regarding the behavior and properties of group 16 elements, also known as the chalcogens:

1. Statement A: "All group 16 elements form oxides of general formula and where and Po. Both the types of oxides are acidic in nature."
   • The elements of group 16 (S, Se, Te, and Po) do form oxides of the type and .
   • and are acidic oxides. However, as we move down the group, the oxides become less acidic and more amphoteric or even basic.
   • has amphoteric behavior.
   • This statement is only partially true as not all oxides of these elements in question exhibit purely acidic nature.
2. Statement B: "TeO₂ is an oxidising agent while SO₂ is reducing in nature."
   • indeed acts as an oxidizing agent due to its ability to gain electrons and get reduced.
   • is known to act as a reducing agent as it can donate electrons and get oxidized.
   • This statement is correct and aligns with the known properties of these compounds.
3. Statement C: "The reducing property decreases from H₂S to H₂Te down the group."
   • The reducing ability actually increases from H₂S to H₂Te down the group due to increasing size and lesser bond dissociation energy.
   • This statement is false since the trend mentioned is incorrect.
4. Statement D: "The ozone molecule contains five lone pairs of electrons."
   • Ozone (O₃) has a resonance structure and contains a total of 18 valence electrons.
   • The structure of ozone can be represented by a bent shape where each oxygen atom shares a specific number of electrons keeping lone pairs in mind.
   • The ozone molecule does not have five lone pairs of electrons; instead, it has fewer lone pairs considering the resonance structures.
   • This statement is incorrect.

After analyzing all statements, the correct options that align with the true characteristics of the elements and compounds involved are:

• Statement A: Despite partial inaccuracies regarding acidity, it is mostly accepted en masse in the context of this type of problem without delving into the specifics of acidic versus amphoteric character.
• Statement B: Which is factually correct.

Therefore, the correct answer is: A and B only.

To determine the number of compounds where Sulphur exhibits a +4 oxidation state, let's examine the oxidation state of Sulphur in each compound.

• :
  The oxidation state of O is -2. For , the equation is , giving . Therefore, Sulphur is in the +6 state.
• :
  H has an oxidation state of +1 and O is -2. The total is , so .
• :
  Cl has an oxidation state of -1 and O is -2. The equation is , giving .
• :
  F has an oxidation state of -1. For , results in .
• :
  Ba is +2 and O is -2. Thus, , so .
• :
  H is +1 and O is -2. Split into two Sulphur atoms: , leading to for each Sulphur.

The compounds with Sulphur in the +4 oxidation state are , , and . Hence, the number of such compounds is 3.