Which one of the following statements regarding Aluminium is not correct?

Aluminium is a highly reactive metal and does not occur in a free (native) state in nature. Instead, it is found in combined forms, primarily as bauxite, which consists of hydrated aluminium oxides [c2][c3][c4]. Statement 1 is correct as aluminium oxide and hydroxide are amphoteric, reacting with both acids and bases [c1][t4]. Statement 3 is correct because concentrated nitric acid renders aluminium passive by forming a thin, protective oxide layer on its surface, making it appear unaffected [t6]. Statement 4 is correct as aluminium reacts with hot concentrated sulphuric acid to produce aluminium sulphate and sulphur dioxide gas, where the acid acts as an oxidizing agent [t1][t3]. Therefore, the statement that aluminium occurs in a free state is the only incorrect one.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.9 > p. 41
2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 9: Distribution of World Natural Resources > Bauxite (aluminium) > p. 33
3. [3] NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 5: Print Culture and the Modern World > Bauxite Bauxite > p. 110
4. [4] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 7: Resources > Natural Resources of India > p. 18
5. [5] https://www.sciencedirect.com/topics/engineering/bauxite-deposits
6. [6] https://www.sciencedirect.com/topics/materials-science/aluminum-coated-steel