Question

$(a)$ What is meant by the reactive series of metals? Arrange the following metals in an increasing order of their activities towards water.
Zinc, iron, magnesium, sodium.
$(b)$ Name one metal more reactive and another less reactive than hydrogen.
$(c)$ Name one metal which displaces copper from copper sulphate solution and one which does not.
$(d)$ Name one metal which displaces silver from silver nitrate solution and one which does not.

Answer 1

Reactive series is used to determine the products of single displacement reactions, whereby metal A will replace another metal B in a solution if A is higher in the series. A metal can displace metal ions listed below in the series.

Complete answer:
$(a)$ A reactive series is a series of metals, arranged by their reactivity from highest to lowest$>$. In general, the more reactive a metal is:
$\bullet$ The more vigorously it reacts with other substances
$\bullet$ The more easily it loses electrons to form positive ions
The reactivity of elements towards water decreases towards the right in a period. It also increases down the group. But zinc is more reactive towards water than iron. Hence the increasing order of their activities toward water is: Sodium $>$Magnesium$>$ Zinc$>$ Iron
$(b)$ Copper is below hydrogen in the reactive series so, copper is less reactive than hydrogen and the second metal that is tin is placed above the hydrogen in the reactivity series, so tin is more reactive than hydrogen. Therefore, copper is less reactive and tin is more reactive than hydrogen.
$(c)$ Silver is a lesser reactive metal than copper as it comes below the copper in the reactive series. It cannot displace copper from its aqueous solution. But zinc is placed above the copper in the reactive series thus, it can displace copper from copper sulphate in the solution.
$Zn + CuS{O_4} \to ZnS{O_4} + Cu$
$Ag + CuS{O_4} \to \times$
$(d)$ copper comes above the silver in the reactive series. Thus, it is more reactive than copper, so it can displace the silver in silver nitrate . whereas gold comes below the reactive series and is less reactive than silver so it cannot displace silver from silver nitrate.
$2AgN{O_3} + Cu \to Cu{(N{O_3})_2} + 2Ag$
$AgN{O_3} + Au \to \times$

Note:
Remember that the reactivity of a metal decreases from top to bottom and the more reactive metal will displace the less reactive metal from the compound in a reaction. Thus, it also helps us to predict a reaction.