Question

when iron nail are kept in copper sulphate solution for some time (a)the nail turns brown after some time (b)there is no change in nail(c)a brown Colour gas is released ​

Answer 1

Explanation:

Option (a) the nail turns brown after some time

is the correct option because iron is more reactive than copper. So, copper particles would get deposited on the iron nail.

Answer 2

Answer

(a) the nail turns brown after some time.

$\rule{200}2$

Explanation

When iron nails are kept in copper sulphate solution for some time.

The following reaction takes place:

$\sf{Fe\:+\:CuSO_4\:\rightarrow\:FeSO_4\:+\:Cu}$

As Fe is more reactive than Cu (according to reactivity series) so, it displaces Cu from CuSO4 and react with Fe to give FeSO4 and Cu. (Iron formed is brown in colour and colour of copper sulphate solution changes from blue to light green.)

Here.. more reactive metal displaces less reactive metal from it's salt solution. So, it is knwon as Displacement reaction.

Now, again coming back to the question.

Iron is more reactive than copper due to this it displaces copper from it's solution. After that reaction (which is shown above) iron becomes ferrous sulphate.

What is reactivity series?

Series of metals in the decreasing order is known as Reactivity series.

K = Potassium

Na = Sodium

Ca = Calcium

Mg = Magnesium

Al = Aluminum

Zn = Zinc

Fe = Iron

Pb = Lead

H = Hydrogen

Cu = Copper

Hg = Mercury

Ag = Silver

Au = Gold

(Reactivity decreases down the group. Means, Potassium is most reactive metal and Gold is least reactive. )