Question
Explain the concept of chemical reactions with two examples.
✓
Answer
→ A chemical reaction is a process where one or more substances (reactants) are converted into new substances (products).
→ This involves the breaking and forming of chemical bonds.
Chemical reactions are usually irreversible, meaning you can't easily go back to the original substances.
Example:
1.Burning Wood
Reactants: Wood (primarily carbon compounds) and Oxygen O2 in the air.
Process: When you light a fire, the wood combines with oxygen in a process called combustion.
Products: Carbon Dioxide CO2,Water H2O,Ash, and Heat/Light.
Explanation: The wood is changed into completely different substances (gases and ash), and you can't turn the ash and gases back into wood.
2.Rusting of Iron
Reactants: Iron (Fe), OxygenO2 and Water H2O
Process: Over time, iron reacts with oxygen and water in the air.
Product: Rust (Iron Oxide, Fe2O3)
Explanation: The shiny iron metal turns into a reddish-brown, flaky substance (rust). The original iron has been transformed into a new compound, and you can’t simply turn the rust back into iron.
→ This involves the breaking and forming of chemical bonds.
Chemical reactions are usually irreversible, meaning you can't easily go back to the original substances.
Example:
1.Burning Wood
Reactants: Wood (primarily carbon compounds) and Oxygen O2 in the air.
Process: When you light a fire, the wood combines with oxygen in a process called combustion.
Products: Carbon Dioxide CO2,Water H2O,Ash, and Heat/Light.
Explanation: The wood is changed into completely different substances (gases and ash), and you can't turn the ash and gases back into wood.
2.Rusting of Iron
Reactants: Iron (Fe), OxygenO2 and Water H2O
Process: Over time, iron reacts with oxygen and water in the air.
Product: Rust (Iron Oxide, Fe2O3)
Explanation: The shiny iron metal turns into a reddish-brown, flaky substance (rust). The original iron has been transformed into a new compound, and you can’t simply turn the rust back into iron.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Define average speed and explain how it is calculated.
Figure shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.
Match the items in Column $I$ with those in Column $II:$
→|
|
Column $I$
|
|
Column $I$
|
|
$(a)$
|
Yeast
|
$(i)$
|
Earthworm
|
|
$(b)$
|
Diaphragm
|
$(ii)$
|
Gills
|
|
$(c)$
|
Skin
|
$(iii)$
|
Alcohol
|
|
$(d)$
|
Leaves
|
$(iv)$
|
Chest cavity
|
|
$(e)$
|
Fish
|
$(v)$
|
Stomata
|
|
$(f)$
|
Frog
|
$(vi)$
|
Lungs and skin
|
|
|
|
$(vii)$
|
Tracheae
|
State some ways to prevent soil erosion.
Rohan went to the desert of Rajasthan with his freinds. He saw an animal. It had a hump. Its feet had large soles. He wondered about this animal. He found that these were adaptations of that animal which helped it to survive in very hot and dry climate of the desert.
Answer the following Questions on the basis of the observations seen by Rohan.
Answer the following Questions on the basis of the observations seen by Rohan.
- Name the animal Rohan observed in the desert of Rajasthan?
- What role does this hump has in this animal?
- Why do it has large soles?
- Can you give same more adaptations of this animal which help it to survive in desert?
- What values do you observe in Rohan?
Assume, a person is standing in front of a plane mirror. The distance between the mirror and his image is $6m$. If the person moves 2m towards the plane mirror, what would be the distance between the person and his image?
→Draw the circuit diagram to represent the circuit shown in figure.
Explain the position and role of the Sun, Moon, and Earth in a solar and a lunar eclipse.
Table : Testing the nature of samples with blue and red litmus papers
| Name of the Sample | Colour of blue litmus paper after putting a drop of sample | Colour of red litmus paper after putting a drop of sample |
| Lemon juice | Red | Red |
| Soap solution | Blue | Blue |
| Amla juice | Red | Red |
| Tamarind water | Red | Red |
| Vinegar | Red | Red |
| Baking soda solution | Blue | Blue |
| Lime water | Blue | Blue |
| Tap water | Blue | Red |
| Washing powder solution | Blue | Blue |
| Sugar solution | Blue | Red |
| Salt solution | Blue | Red |
| Orange juice | Red | Red |
Match the words of Column $I$ with those given in Column $II:$
→|
|
Column I
|
|
Column II
|
|
$1.$
|
Scouring
|
$(a)$
|
Yields silk fibres
|
|
$2.$
|
Mulberry leaves
|
$(b)$
|
Wool yielding animal
|
|
$3.$
|
Yak
|
$(c)$
|
Food of silk worm
|
|
$4.$
|
Cocoon
|
$(d)$
|
Reeling
|
|
|
|
$(e)$
|
Cleaning sheared skin
|