Oxides

The problem asks to identify the amphoteric oxides from a given list of p-block element oxides and determine their total number.

Concept Used:

The nature of an oxide (acidic, basic, amphoteric, or neutral) depends on the element and its oxidation state. The classification is as follows:

• Acidic Oxides: These are typically oxides of non-metals (e.g., ). They react with bases to form salt and water. The acidic character increases with the increasing oxidation state of the central non-metal.
• Basic Oxides: These are oxides of metals (e.g., ). They react with acids to form salt and water.
• Amphoteric Oxides: These oxides exhibit both acidic and basic properties. They react with both acids and bases to form salt and water. Oxides of elements near the metal-nonmetal boundary in the periodic table, such as Al, Zn, Sn, and Pb, are typically amphoteric.
• Neutral Oxides: These oxides do not react with either acids or bases. Common examples are and .

Step-by-Step Solution:

We will classify each oxide from the given list:

Step 1: Classify each oxide.

1. (Dichlorine heptoxide): Chlorine is a non-metal in its highest oxidation state (+7). This is a strongly acidic oxide. It is the anhydride of perchloric acid ( ).
2. (Carbon monoxide): This is a well-known neutral oxide. It does not exhibit acidic or basic properties.
3. (Lead(IV) oxide): Lead is a metal. Its oxides are known to be amphoteric. It reacts with both acids and bases. For example:
   With acid:
   With base: (Sodium plumbate)
   Thus, it is amphoteric.
4. (Dinitrogen monoxide): This is another example of a neutral oxide.
5. (Nitrogen monoxide): This is also a neutral oxide.
6. (Aluminum oxide): Aluminum is a metalloid-like metal, and its oxide is a classic example of an amphoteric substance. It reacts with both acids and bases:
   With acid:
   With base: (Sodium aluminate)
   Thus, it is amphoteric.
7. (Silicon dioxide): Silicon is a metalloid. Its oxide is acidic. It reacts with strong bases to form silicates but does not react with most acids (except hydrofluoric acid).
8. (Dinitrogen pentoxide): Nitrogen is a non-metal in a high oxidation state (+5). This is a strongly acidic oxide, being the anhydride of nitric acid ( ).
9. (Tin(IV) oxide): Tin is a metal whose oxides are amphoteric. It reacts with both strong acids and strong bases:
   With acid:
   With base: (Sodium stannate)
   Thus, it is amphoteric.

Step 2: Count the amphoteric oxides.

From the classification above, the oxides that are amphoteric in nature are:

Counting these oxides, we find there are a total of three.

Final Result:

The number of oxides having amphoteric nature in the given list is 3.

Step 1: Statement (I) is incorrect because elements on the extreme left of the periodic table, such as alkali metals and alkaline earth metals, form basic oxides, not acidic oxides.

Step 2: Statement (II) is correct because non-metals, which are on the extreme right of the periodic table, form acidic oxides when they react with water.

For example, sulfur dioxide ( ) reacts with water to form sulfurous acid ( ).

Thus, the correct answer is that Statement I is false but Statement II is true.