Question

Strip of cu is placed in 4 different colourless soln - potassium nitrate, silver nitrate, zinc nitrate, calcium nitrate. Which will turn blue?

Answer 1

$\bold{REACTIVITY \: SERIES}$

Its the series in which elements are arranged in the decreasing order of their reactivity.

• The highly reactive metals are highly reactive are placed above
• The less reactive metals are placed in middle .
• Least reactive metals are kept at bottom.

• The metals above can replace other metals in their compound, which lies below them in reactivity series.

$\bold{Reactivity \:series}\\\\K\\Na\\Ca\\Mg\\Al\\Zn\\Fe\\Sn\\Pb\\H\\Cu\\Hg\\Ag$

$\bold{According \: to \: question}$

A copper strip in placed in solution of

• Potassium nitrate.

Since, copper lies below potassium in reactivity series so potassium will not be displaced and the solution will remain unaffected.

• Silver nitrate

Silver lies below copper in reactivity series so copper will displace silver and will form copper nirate and solution will turn blue.

• Calcium nitrate

Calcium lies above copper in reactivity series so i will not be displaced by copper and the solution will remain unaffected.

• Zinc nitrate

Zinc lies above copper in reactivity series so it will not be displaced by copper and hence the solution will remain unaffected.

So we can convey that $\bold{silver \: nitrate \: will \: change \:its \: colour \: to \: blue}$

Answer 2

Silver nitrate is the answer...!!!