An aqueous solution of zinc sulphate was taken in four test tubes. Zinc, Iron, Copper and Aluminium pieces were dropped into separate test tubes as given below : I (Zn), II (Fe), III (Cu), IV (Al). A reaction will be observed in test tubes

Metals and Non-metals

Chemical Properties of Metals

Options

(A)I and II

(B)I and III

(C)II and III

(D)only IV

Official Answer

Reactivity seriesAluminiumZinc sulphateDisplacementMore reactive

Marking Scheme

1Analysis of reactivity series for Al, Zn, Fe, and Cu (0.5 marks)
2Conclusion that only Al is more reactive than Zn (0.5 marks)

Hint

Compare the positions of Zn, Fe, Cu, and Al in the reactivity series. Only a metal higher than Zinc can displace it from its sulphate solution.

Quick Oral Answer

A reaction only occurs in the test tube containing Aluminium because, according to the activity series, Aluminium is the only metal among the choices that is more reactive than Zinc.

Analysis & Explanation

Based on the Reactivity Series provided in Table 3.2, the order of reactivity for the given metals is $Al > Zn > Fe > Cu$ . A displacement reaction (Section 3.2.4) occurs only when a more reactive metal is added to the salt solution of a less reactive metal.

In test tube I, Zinc ( $Zn$ ) is added to Zinc sulphate ( $ZnSO_4$ ); no reaction occurs between a metal and its own salt.
In test tube II, Iron ( $Fe$ ) is below Zinc in the reactivity series, so it cannot displace Zinc.
In test tube III, Copper ( $Cu$ ) is much lower than Zinc in the reactivity series, so no reaction occurs.
In test tube IV, Aluminium ( $Al$ ) is above Zinc in the reactivity series. Therefore, Aluminium will displace Zinc from Zinc sulphate: $2Al(s) + 3ZnSO_4(aq) \rightarrow Al_2(SO_4)_3(aq) + 3Zn(s)$ .

Thus, a reaction is observed only in test tube IV.

Common Mistakes

1Assuming Iron can displace Zinc because it is a 'strong' metal.
2Forgetting that a metal cannot react with its own salt solution in a displacement context.

Interesting Facts

The reactivity series is a practical tool developed by observing these very displacement reactions in the lab.

Spotted a mistake or something unclear?

Tell us — we fix reported answers fast.

Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2011?

This question carries 1 mark in the CBSE Class 10 Science 2011 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Metals and Non-metals" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Chemical Properties of Metals" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2011 paper?

This is a MCQ question from Section B in the CBSE Class 10 Science 2011 paper.