Which of the following represents an order of increasing reactivity?

Analysis

The question asks for the order of increasing reactivity of metals. This means we must arrange the metals starting from the least reactive to the most reactive. This concept is based on the Electrochemical Series (or the Activity Series of metals).

Concept Explanation

The reactivity series ranks metals based on their tendency to lose electrons (oxidation). Metals at the top of the series are highly reactive (they lose electrons easily), while metals at the bottom are noble or less reactive.

The standard order for these specific metals is: Au (Gold) < Cu (Copper) < Sn (Tin) < Fe (Iron) < Ca (Calcium)

• Gold (Au): A noble metal, very unreactive.
• Copper (Cu): Less reactive than hydrogen; does not displace hydrogen from acids.
• Tin (Sn): Moderately reactive.
• Iron (Fe): More reactive than tin; readily rusts.
• Calcium (Ca): A highly reactive alkaline earth metal that reacts vigorously with water.

Step-by-Step Solution

1. Identify the metals: We have Gold (Au), Copper (Cu), Tin (Sn), Iron (Fe), and Calcium (Ca).
2. Determine their positions in the reactivity series: • Calcium (Ca) is the most reactive among the group. • Iron (Fe) is more reactive than Tin (Sn). • Tin (Sn) is more reactive than Copper (Cu). • Copper (Cu) is more reactive than Gold (Au).
3. Arrange in increasing order (Least to Most): • Start with the least reactive: Au • Next: Cu • Next: Sn • Next: Fe • End with the most reactive: Ca
4. Resulting sequence: Au < Cu < Sn < Fe < Ca.

Conclusion

Comparing our result with the given options, we see that option A matches our derived sequence perfectly.

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Exam Tip

To remember the reactivity series, use a mnemonic like: "Please Stop Calling Me A Careless Zebra Instead Try Learning How Copper Saves Gold." (Potassium, Sodium, Calcium, Magnesium, Aluminium, Carbon, Zinc, Iron, Tin, Lead, Hydrogen, Copper, Silver, Gold).