Question

(I) \(\mathrm{V}_{2} \mathrm{O}_{5}, \mathrm{Cr}_{2} \mathrm{O}_{3}\) are amphoteric oxides. (II) Interstitial compounds are very reactive (III) In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine. Correct statements amongs the following are- (1)?, II (2) II, III (3) I, III (4) I, II

Short answer

I, III are correct statements

Step-by-step solution

Identify Amphoteric Oxides

Amphoteric oxides are those that can react with both acids and bases to form salts and water. Check if the given compounds \(\text{V}_2 \text{O}_5\) and \(\text{Cr}_2 \text{O}_3\) fall under this category by verifying their reactivities. \(\text{Cr}_2 \text{O}_3\) and \(\text{V}_2 \text{O}_5\) are known amphoteric oxides. Thus, statement (I) is correct.

Evaluate Reactivity of Interstitial Compounds

Interstitial compounds are typically formed when small atoms like hydrogen, carbon, or nitrogen occupy the interstitial spaces in a metal lattice. These compounds exhibit high hardness and reduced reactivity. Hence, the statement (II)’s assertion about high reactivity is incorrect.

Check Stability of Compounds of Manganese in Higher Oxidation States with Oxygen and Fluorine

In higher oxidation states, manganese (Mn) forms stable compounds, particularly with highly electronegative elements like oxygen and fluorine. Example: \(\text{MnO}_4^-\) Therefore, statement (III) is correct.

Key concepts

Amphoteric Oxides

Amphoteric oxides are unique because they can react with both acids and bases. This dual behavior allows them to form salts and water in both types of reactions. For instance, consider \(\mathrm{V}_{2} \mathrm{O}_{5}\) and \(\mathrm{Cr}_{2} \mathrm{O}_{3}\), both of which are known amphoteric oxides. Let's break this down.

When \(\mathrm{Cr}_{2} \mathrm{O}_{3}\) reacts with acids like hydrochloric acid, it forms chromium chloride and water. Similarly, it can react with bases like sodium hydroxide to produce sodium chromate and water.

This ability to react with both acids and bases makes amphoteric oxides an interesting topic in inorganic chemistry. Remember, not all metal oxides show this property. Be sure to recognize the reactivity patterns of different oxides when studying for exams like IIT JEE.

Interstitial Compounds

Interstitial compounds are fascinating due to their unique structure and properties. These compounds form when small atoms such as hydrogen, carbon, or nitrogen occupy the spaces (interstices) within a metal lattice.

Several distinct features characterize interstitial compounds:

• High Hardness: They are significantly harder than the pure metals from which they form.
• Reduced Reactivity: Contrary to what might be assumed, interstitial compounds are often less reactive than their constituent elements. This is essential to keep in mind; for example, interstitial compounds are used in making cutting tools because they do not easily react with other substances.
• High Melting Points: These compounds have high melting points due to the stable structure provided by the small atoms within the metal lattice.

Understanding these properties can significantly help when answering questions related to their reactivity and uses.

Oxidation States Stability

Oxidation states are crucial in understanding the chemical behavior of elements. Manganese (Mn) provides an excellent example of variable oxidation states. In its higher oxidation states, manganese forms particularly stable compounds, especially when combined with highly electronegative elements like oxygen and fluorine.

For instance, in \(\mathrm{KMnO}_{4}\) (potassium permanganate), manganese has an oxidation state of +7, indicating a highly stable configuration. This stability is due to the strong bonding with oxygen atoms. Similarly, manganese forms stable compounds with fluorine, another highly electronegative element, stabilizing even higher oxidation states.

Mn's ability to form stable high oxidation state compounds is a key concept and can help explain various reactions and properties in the exam context. Understanding oxidation states' stability is essential for predicting the behavior of transition metals in chemical reactions.