Cls 10 sci chp 1 mcq

 

 Class 10 Science 

 Chapter 1 Chemical Reactions and Equations 

 Multiple Choice Questions 

1. Give the ratio in which hydrogen and oxygen are present in water by volume.

(a) 1:2           (b) 1:1          (c) 2:1          (d) 1:8

Ans: (c) 2:1

2. Which of the following is a displacement reaction?

(a) MgCO₃ → 2MgO + CO₂

(b) 2Na + 2H₂O  → 2NaOH + H₂

(c) 2H₂ + O₂ → 2H₂O

(d) 2Pb(NO₃) → 2PbO + 4NO₂ + O₂

Ans: (b) 2Na + 2H₂O  → 2NaOH + H₂

3. The chemical formula of magnesium oxide is?

(a) MgO₂          (b) Mg₂O         

(c) MgO           (d) Mg(OH)₂

Ans: (c) MgO

4. Which of the reactions is used in black and white photography?

(a) Combination Reaction     

(b) Decomposition Reaction

(c) Displacement reaction      

(d) Oxidation reaction

Ans: (b) Decomposition Reaction

5. Which of the following does show an oxidation reaction?

(a) Gain of oxygen             

(b) Loss of oxygen

(c) Gain of hydrogen         

(d) None of the above

Ans: (a) Gain of oxygen

6. Magnesium ribbon is rubbed before burning because it has a coating of

(a) basic magnesium carbonate        

(b) basic magnesium oxide

(c) basic magnesium sulphide          

(d) basic magnesium chloride

Ans: (a) basic magnesium carbonate

7. Which of the following statements about the given reaction are correct?

3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

(i) Iron metal is getting oxidised               

(ii) Water is getting reduced

(iii) Water is acting as reducing agent      

(iv) Water is acting as oxidising agent

(a) (i), (zi) and (iii)

(b) (in) and (iv)                                                     

(c) (i), (ii) and (iv)

(d) (ii) and (iv)

Ans: (c) (i), (ii) and (iv)

8. A substance ‘X’ is used in white-washing and is obtained by heating limestone in the absence of air. Identify ‘X’.

(a) CaOCl₂        (b) Ca(OH)₂

(c) CaO             (d) CaCO₃

Ans: (c) CaO

9. When Ag is exposed to air it gets a black coating of

(a) AgNO₃        (b) Ag₂S        

(c) Ag₂O          (d) Ag₂CO₃

Ans: (b) Ag₂S

10. What type of chemical reactions take place when electricity is passed through water?

(a) Displacement              

(b) Combination

(c) Decomposition            

(d) Double displacement

Ans: (c) Decomposition

11. Which of the following reactions can also be termed as thermal decomposition reaction?

(a) Combination Reaction                  

(b) Decomposition Reaction

(c) Displacement reaction                   

(d) Double displacement reaction

Ans: (b) Decomposition Reaction

12. A student performs an experiment to form aluminium chloride from aluminium and chlorine. Which options give the chemical equation of the reaction?

(a) Al + Cl₂ → AlCl₂               

(b) 2Al + Cl₂ → 2AlCl

(c) 2Al + 3Cl₂ → 2AlCl₃        

 (d) 3Al + 3Cl₂ → 3AlCl₃

Ans: (c) 2Al + 3Cl₂ → 2AlCl₃

13. One of the following processes does not involve a chemical reaction, that is:

(a) Melting of candle wax when heated

(b) Burning of candle wax when heated

(c) Digestion of food in your stomach

(d) Ripening of banana

Ans: (a) Melting of candle wax when heated

14 From the following which one is the example of chemical reaction?

(a) Grapes get fermented          

(b) Breakdown of food

(c) Formation of curd              

 (d) All of the above

Ans: (d) All of the above

15. What happens when lead nitrate reacts with potassium iodide?

(a) They will not react

(b) Large amount of hydrogen release

(c) Yellow ppt of lead iodide and potassium nitrate will be produced

(d) Evolution of gas will occur

Ans: (c) Yellow ppt of lead iodide and potassium nitrate will be produced

16. Which of the following are exothermic processes?

(i) Reaction of water with quick lime     

(ii) Dilution of an acid

(iii) Evaporation of water                       

(iv) Sublimation of camphor (crystals)
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)

Ans: (a) (i) and (ii)

17. MnO₂ + 4HCl → ₂ + 2H₂O + Cl₂
identify the substance oxidized in the above equation.

(a) MnCl₂        (b) HCl         

(c) H₂O         (d) MnO₂

Ans: (d) MnO₂

18.  A substance added to food containing fats and oils is called:
(a) Oxidant      (b) Rancid       

(c) Coolant      (d) Antioxidant

Ans: (d) Antioxidant

19. Which of the following gases can be used for storage

(a) Carbon dioxide or Oxygen            

(b) Nitrogen or Oxygen

(c) Carbon dioxide or Helium            

(d) Helium or Nitrogen   

Ans: (d) Helium or Nitrogen       

20. Pb + CuCl₂ → PbCl₂ + Cu
The above reaction is an example of:

(a) combination        

(b) double displacement        

(c) decomposition        

(d) displacement 

Ans:  (d) displacement 

21. The gas liberated at the cathode in the electrolysis of water is ( March 2022)

(A) Oxygen

(B) Hydrogen

(C) Chlorine

(D) Nitrogen. 

Ans: (B) Hydrogen

22. Fe2O3 + 2 Al → Al2O3 + 2 Fe The type of above chemical reaction is (June 2019)

A) combination reaction

(B) double displacement reaction

(C) decomposition reaction

(D) displacement reaction

Ans: (D) displacement reaction

23. The reaction in which two compounds exchange their ions to form two new compounds. (KREIS Mid Term-22)

a) redox reaction

b) double displacement reaction

c) combination reaction

d) displacement reaction

Ans: b) double displacement reaction