Class 10 Solutions Chemical Reactions And Equations

1.State whether the following statement is true or false :
A chemical equation can be balanced easily by altering the formula of a reactant or product.
Solution :
False.

2.What does the symbol (aq) represent in a chemical equation ?
Solution :
The symbol (aq)
represents aqueous solution in a chemical equation.

3.What is wrong with the following chemical equation ?
Mg + O ——— > MgO
Correct and balance it.
Solution :
Oxygen should be in molecular form, O2 
2Mg + O2 —–> 2MgO

4.Why is photosynthesis considered an endothermic reaction ?
Solution :
Photosynthesis is an
endothermic reaction because sunlight energy is absorbed by green plants
during this process.

5.How will you indicate the following effects in a chemical equation ?
(a) A solution made in water
(b) Exothermic reaction
(c) Endothermic reaction
Solution :
(a) Aqueous solution is indicated by the symbol ‘aq’.
An exothermic reaction is indicated by writing “+Heat” or “+Heat energy”  or “+Energy” on the products side of an equation.
An endothermic reaction is indicated by writing “+Heat” or “+Heat energy”  or “+Energy” on the reactants side of an equation