Question

solve if you can (all) challenge

Ques1. On what chemical law, balancing of chemical equation is based?
Ques2. Give an example of photo chemical reaction.
Ques3. Name a reaction which forms insoluble salts.
Ques4. Explain the following in terms of gain and loss of oxygen with one example:
a. Oxidation
b. Reduction
Ques5. A copper coin is kept in a slotuion of silver nitrate for some time, what will happen to the coin and the colour of the solution?
Ques6. Why do we apply paint on iron articles?
Ques7. What happens chemically when quicklime is added to water?
Ques8. Name the types of reactions in the following:
a. Garbage producing foul smell
b. Burning of natural gas
c. Carbon Dioxide gas passed through lime water
Ques9. Blue crystals of copper sulfate on heating in a dry test tube bocome colourless. Give reason.
Ques10. Why can not a chemical change be reversed normally?
Ques11. Can rusting of iron take place in distilled water?

Answer 1

Here are some of the ans....
1 ans. Balancing of chemical equation is based on law of conservation of mass...

2 ans. Eg: photosynthesis of HCl..

3 ans. Precipitation reaction...

4 ans. Oxidation : the reactions in which gain ofoxygen takes place are called oxidation.
Ex : 2 u +O2 ➡2 up

Reduction : the reactions in which loss of oxygen takes place are called reduction.
Ex: ZnO +C ➡Zealand +co

5 ans.copper is more effective than a silver metal and hence when copper coin is kept immersed in silver nitrate solution for some time, it displaces silver frm silver nitrate solution.
Cu+2AgNO3 ➡Cu(NO3)2 + 2AgNO3

6 ans. We generally apply paint on iron to prevent them frm rusting.

7 ans. When calcium oxide is added to water, it reacts vigorously with water to produce slaked lime.

8 ans. A. Decomposition reaction
B.combustion reaction
C.displacement reaction

9 ans. On heating copper sulfate the hydrous crystal of copper change into colourless because the 5 water molecules associated with it evaporates...so it changes into colour less

10 ans. Any chemical change is simply a chemical reaction ,to reverse it we have to maintain proper temperature and pressure conditions to make it happen.

11 ans. Yes, rusting of iron can take place in distilled water, distilled water can readily absorb oxygen frm the atmosphere when compared to normal tap water. So,this as a result helps in rusting.


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