Chemical Reactions and Equations - Answers of NCERT Science Textbook In-Text Questions - 10th CBSE Chemistry Solutions


Class 10 Ncert Cbse Solutions of Science (Chemistry)

 Chapter 1, Chemical Reactions and Equations

Answers of NCERT Science Textbook In-Text Questions

Chemical Reactions and Equations | Class 10 NCERT (CBSE) Science (Chemistry) Textbook In-Text Questions [Click here to view questions]

(Page 6)
Answer.1: Magnesium ribbon is a very reactive metal. When stored it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide being a stable compound prevents further reaction of magnesium with oxygen. The magnesium is cleaned before burning in air to remove this layer so that the metal can be exposed to air properly.   
(i) H2 (g) + Cl2 (g) –––> 2HCl (g)
(ii) 2Na (s) + 2H2O (liq) –––> 2NaOH (aq) + H2 (g).
(i) BaCl2 (aq) + Na2SO4 (aq) –––> BaSO4 (s) + 2NaCl (aq)
(ii) NaOH (aq) + HCl (aq) –––> NaCl (aq) + H2O (liq)
 (Page 10)  
(i) The substance X is lime which is used for white washing. Its formula is CaO.
(ii) CaO + H2O –––> Ca(OH)2 + Heat
Answer.2: water contains two parts of hydrogen and one part oxygen. Therefore, during the electrolysis of water the amount of hydrogen gas collected in one of the test tubes is double than that of the oxygen produced and collected in the other test tube.  
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Answer.1: Iron is more reactive than copper. So, when an iron nail is dipped in a copper sulphate solution, iron displaces copper from its solution to form iron sulphate, which is green in color.
Fe (s) + CuSO4 (aq) –––> FeSO4 (aq) + Cu (s)   
Hence, the blue color of copper sulphate solution changes into green color because of this displacement reaction.  
Ans: When lead (II) nitrate is mixed with potassium iodide, potassium nitrate and lead iodide are formed.
Pb(NO3)2 + 2KI –––> 2KNO3 + PbI2
Na2CO3 (aq) + CaCl2 (aq) –––> CaCO3 (s) + 2NaCl (aq)
Here sodium carbonate and calcium chloride exchange ions to form two new compounds.
(i) Sodium (Na) is oxidized to Na2O.
(ii) CuO (Copper oxide) is reduced to Cu, while H2 gas is oxidized to H2O.

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