Question

Which of the following symbols is used to show solid precipitate?
A. $ \downarrow $
B. $ \uparrow $
C. $\rightleftharpoons$
D. None of these

Answer 1

Hint: We know that precipitates are the insoluble solids formed in a chemical reaction. The reactions in which precipitates are formed are called precipitation reactions. For example, when sodium chloride undergoes reaction with silver nitrate, formation of silver chloride (precipitate) takes place.

Complete step by step answer:
Let’s understand chemical reaction and its characteristics. A chemical reaction is a chemical change in which the chemical composition of a substance is changed and one or more new substances with different chemical composition is formed.

Let’s discuss some characteristics of the chemical reaction. Some chemical reactions are characterized by changes that are quite easily observed. These changes are:

1) Formation of precipitate: Some chemical reaction forms insoluble solids (precipitates). The formation of precipitate is indicated by the sign of $ \uparrow $.

2) Evolution of gas: Some chemical reactions produce gas such as reaction of zinc and sulphuric acid produces zinc sulphate and hydrogen gas. The formation of gas is indicated by the sign of $ \uparrow $.

3) Change of colour: Certain chemical reactions are characterized by a change in the colour of reactants. For example, when we add some pieces of iron to the green colored copper sulphate solution, the color of the solution turns light green.

4) Change of state: In many chemical reactions the formed product possesses a different state than the reactant.
So, the sign that indicates the formation of solid precipitate is $ \uparrow $.

Hence, the correct choice is option B.

Note: Always remember that the double arrow sign ($\rightleftharpoons$) indicates that the reaction is reversible. Reversible reactions are those reactions in which reactants can become products and products can become reactants. For example, melting of ice to water.