Chemical Reactions and Equations — Class 10 Science PYQs

Select from the following a decomposition reaction in which source of energy for decomposition is light :

Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction

When $2$ mL of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as :

Select from the following a process in which a combination reaction is involved :

${\text{MnO}}_2+\text{4HCl}\to {\text{MnCl}}_2+{\text{2H}}_2\text{O}+{\text{Cl}}_2$

The reaction given above is a redox reaction because in this case :

Identify the correct statement about the following reaction :

$2{\text{H}}_2\text{S}+{\text{SO}}_2⟶2{\text{H}}_2\text{O}+\text{S}$

(a) Define a decomposition reaction. Write an equation to show thermal decomposition of ferrous sulphate crystals.

OR

(b) What is meant by a balanced chemical equation ? Why is it necessary for the equation to be balanced ?

(a) "No precipitation reaction can occur without exchange of ions between the two reactants." Justify this statement giving a balanced chemical equation for the reaction.

OR

(b) Giving one example of each, differentiate between a displacement reaction and a double displacement reaction.

Translate the following statement into a balanced chemical equation.
"When barium chloride reacts with aluminium sulphate, aluminium chloride and barium sulphate are formed."

State the type of this reaction giving reason to justify your answer.

Translate the following statements into chemical equations and then balance them :
(i) Solution of barium chloride and aluminium sulphate in water react to give insoluble barium sulphate and the solution of aluminium chloride.
(ii) Aluminium metal reacts with steam to give aluminium oxide and hydrogen gas.