Metals in the middle of the activity series are commonly found in the earth's crust primarily in which forms?

Correct Option

The correct option is Oxides, sulphides or carbonates.

Explanation

The natural occurrence of metals in the earth's crust is governed by their chemical reactivity. The Reactivity Series (or Activity Series) classifies metals into high, medium, and low reactivity. This position determines whether a metal is found in its native state or combined with other elements such as oxygen, sulphur, or carbon.

Analysis of Metal Occurrence

Metals are grouped based on their reactivity, which dictates their primary ores:

• Metals of Medium Reactivity: Metals in the middle of the activity series (e.g., Iron, Zinc, Lead, Copper) are moderately reactive. They are usually present in the earth's crust as sulphides or carbonates. For example, Zinc occurs as Zinc Blende (ZnS) or Calamine (ZnCO₃). Iron is commonly found as oxides (Haematite, Fe₂O₃) or sulphides (Iron Pyrites, FeS₂). Therefore, these metals are primarily found as oxides, sulphides, or carbonates.
• Metals of High Reactivity: Metals at the top of the series (e.g., Potassium, Sodium, Calcium, Magnesium) are so reactive that they are never found in nature as free elements. They typically occur as chlorides or oxides.
• Metals of Low Reactivity: Metals at the bottom of the series (e.g., Gold, Silver, Platinum) are the least reactive and are often found in the free (native) state.

Key Takeaway: Metals in the middle of the reactivity series (Zn, Fe, Pb, Cu) are moderately reactive and are primarily found in nature as oxides, sulphides, or carbonates, unlike highly reactive metals which often occur as chlorides.