Chhattisgarh State Board Class 9 Science Chapter 10 Chemical Reactions and Equations Exercise Multiple Choice, Fill in the Blanks, Questions and Answers here.
Chhattisgarh State Class 9 Science Chapter 10 Solution
1) Choose the correct option:
(i) Which of the following reactions s taking place when hydrogen chloride is formed by reaction between hydrogen and chlorine
(a) Decomposition (b) Displacement
(c) Combination (d) Double displacement.
Ans: – Option (c) combination.
(ii) Fe2O3 + 2Al –> Al2O3 + 2Fe This reaction is an example of
(a) Combination (b) Decomposition
(c) Displacement (d) Double displacement.
Ans: – Option (c) Displacement.
(iii) 2PbO(s) + C(s) –>2Pb(s) + CO2
(g) Which statement is true about this reaction
(1) Lead is undergoing oxidation
(2) Carbon dioxide is undergoing oxidation
(3) Carbon is getting oxidized to carbon dioxide
(4) Lead oxide is being reduced to lead
(a) 1 and 2 (b) 3 and 4
(c) 2 and 3 (d) all.
Ans: – Option (b) 3 and 4.
(iv) NaCl(aq) + AgNO3(andà AgCl + NaNO3(aq)
The given chemical reaction is
(a) Displacement (b) Combination
(c) Decomposition (d) Double displacement.
Ans: – Option (d) Double displacement.
2) Fill in the blanks
(a) Substances on the LHS in a chemical equation are called ……….. reactants……………… and thoseon the RHS are known as…. product……………
(c) The arrow between the reactants and products in a chemical equation shows the…….. chemical reaction taking places between the two compounds……………….. of a reaction.
(d) The type of reactions where heat is absorbed during the formation of products are……….. endothermic……… reactions.
3) What is a chemical equation? Why should chemical equations be balanced?
Ans: – The representation of substance in any type of balance reaction is known as the chemical reaction. As all we know that the mass of any reactant will be equal with the productmasses so the chemical reaction will be balanced all times.
4) Write balanced chemical equations for the following reactions:
(a) Potassium metal reacting with water to give potassium hydroxide and hydrogen gas.
Ans: – 2K + 2H2O –> 2KOH + H2.
b) Nitrogen gas combines with hydrogen to form ammonia.
Ans: –3H2 + N2 –> 2NH3;
c)Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
Ans: – 2H2S + 3O2 –> 2SO2 + 2H2O;
d) Barium chloride reacts with aluminium sulphate to give a solution of aluminium chloride anda precipitate of barium sulphate.
Ans: – Al2(NO4)3 + 3BaCl2 –> 2AlCl3 + 3BaSO4;
5) Balance the following chemical equations.
(i) C3H8 + O2 –> H2O + CO2;
Ans: – C3H8 + 5O2 –> 4H2O + 3CO2;
(ii) C6H12O6 –> C2H5OH + CO2;
Ans: – C6H12O6 –> 2C2H5OH + 2CO2;
(iii) Hg (NO3)2 + KI –> HgI2 + KNO3;
Ans: – Hg(NO3)2 + 2KI –> HgI2 + 2KNO3;
(iv) HNO3 + Ca(OH)2 –> Ca(NO3)2 + H2O.
Ans: – 2HNO3 + Ca(OH)2 –> Ca(NO3)2 + 2H2O;
6) Write the balanced chemical equation for the following and identify the type of reaction in each case.
(a) Magnesium + iodine –> magnesium iodide.
Ans: -2Mg + I2 –> 2MgI;
b) Magnesium + hydrochloric acid –> magnesium chloride + hydrogen.
Ans: – Mg + 2HCl –> MgCl2 + H2;
c)Zinc + copper nitrate–> zinc nitrate + copper.
Ans: – Zn + Cu(NO3)2 –> Zn(NO3)2 + Cu;
d) Sodium hydrogen carbonate –> sodium carbonate + carbon dioxide + water.
Ans: – 2NaHCO3 –> Na2CO3 + CO2 + H2O.
7) Why are decomposition reactions called the opposite of combination reactions? Write equations forthese reactions.
Ans: – The combination reactions are the reaction in which two or more atoms are forms a new compound or in a decomposition reaction any compound decompose in various compound.
CaCO3 –> CaO + CO2;
8) Write one equation each for decomposition reactions where energy is supplied in the form of heat,light or electricity.
Ans: – while applying heat to the calcium carbonate it dissociate in various compound. This reaction is known as the decomposition reaction in which calcium oxide and carbon dioxide are formed.
CaCO3 –> CaO + CO2;
9) What is the difference between displacement and double displacement reactions? Write equations for these reactions.
Ans: –
Displacement reaction | Double displacement reaction |
Less reactive elements are displaced by more reactive and form compound. | In this reaction two reactants are exchange their compound. |
Mg + 2HCl –>MgCl2 + H2. | MgCl2 + 2KOH –> Mg(OH)2 + 2KCl. |
10) Give two examples of redox reactions.
Ans: – The example of redox reaction is –
CuO + H2 –> Cu + H2O; Fe3O4 + 4H2 –> 3Fe + 4H2O;
11) Explain the chemical reactions that take place in the presence of sunlight.
Ans: – The photosynthesis reaction are taking places in the presence of the sunlight. In this reaction the water is collected by the leaves from ground and from the air it takes the CO2 and release the oxygen gas by which we can do our respiratory works.
12) What do you understand by precipitation reactions? Explain using examples.
Ans: – AgNO3 + NaCl –> AgCl + NaNO3;
The upper reaction is known as the precipitation reaction in which the AgCl is precipitate are formed. As we all know when the two-reactance mixing together form a solid precipitate then this reaction is known as the precipitation reaction.
13) Explain exothermic and endothermic reactions through examples.
Ans: –
Exothermic reaction | Endothermic reaction |
In exothermic reactions the energy is released from the reaction. | In a endothermic reaction the energy is absorbed from the outer sources to the reaction. |
Heat release to the surrounding. | Heat absorbs from surrounding. |
Example: – ice melting, photosynthesis reaction. | Example: – settling reaction, nuclear fission. |
14) Hanif burnt a magnesium ribbon using a spirit lamp and on the basis of his observations he said thatthe type of chemical reaction taking place is combination as well as exothermic as well as oxidation.Do you agree with Hanif? Give reasons for your answer and explain.
Ans: – The reaction between the magnesium and the oxygen present in the air is an exothermic reaction as after this reaction the magnesium oxide white powder is produced and also the energy is produces. So Hanif conclusion about this experiment is valid. The balance chemical reaction of this reaction is –
2Mg + O2 –> 2MgO;
Thanks a lot to you sir because my annual exams ar coming soon and I have not complete my notes…