CBSE Class 10 Science 2018 · Paper 31/1 · Question 6

Chemical Reactions and Equations 3 marks Medium

Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity.

Answer

Heat decomposes $CaCO_{3}$ into $CaO$ and $CO_{2}$ , sunlight decomposes $AgCl$ into $Ag$ and $Cl_{2}$ , and electricity decomposes water into $H_{2}$ and $O_{2}$ .

Heat (thermal decomposition):

CaCO_{3} (s) heat CaO (s) + CO_{2} (g)

Light (photolytic decomposition):

2 AgCl (s) sunlight 2 Ag (s) + Cl_{2} (g)

Electricity (electrolytic decomposition):

2 H_{2} O (l) electricity 2 H_{2} (g) + O_{2} (g)

Other correct equations also earn the marks, for example

2 FeSO_{4} (s) heat Fe_{2} O_{3} (s) + SO_{2} (g) + SO_{3} (g)

for heat and

2 AgBr (s) sunlight 2 Ag (s) + Br_{2} (g)

for light.

🔒 Step-by-step solution

CBSE Class 10 Science 2018 · Paper 31/1 · Question 6

Answer

From the board papers

More questions from Chemical Reactions and Equations