ncert solutions for class 10 science chapter 1
ncert solutions for class 10 science chapter 1
- H2 + Cl2 = 2HCl
- 3BaCl2 + Al2(SO4)3 = 3BaSO4 + 2AlCl3
- 2Na + 2H2O = 2NaOH + H2
- BaCl2(aq) + Na2SO4(aq) = BaSO4(s) + 2NaCl(aq)
- NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(L)
- A solution of substance X is used for white-washing is Calcium oxide and its formula is CaO.
- Reaction of substance X with water is,
CaO + H2O = Ca(OH)2
ncert solutions for class 10 science exercise questions
Ans:-
(a) 3H2 + N2 = 2NH3
(b) 2H2S + 3O2 = 2H2O + 2SO2
(c) 3BaCl2 + Al2(SO4)3 = 2AlCl3 + 3BaSO4
(d) 2K + 2H2O = 2KOH + H2
Q.6.
Ans:-
(a) 2HNO3 + Ca(OH)2 = Ca(NO3)2 +2 H2O
(b) 2NaOH + H2SO4 = Na2SO4 + 2H2O
(c) NaCl + AgNO3 = AgCl + NaNO3
(d) BaCl2 + H2SO4 = BaSO4 + 2HCl
Q.7.
Ans;-
(a) Ca(OH)2 + CO2 = CaCO3 + H2O
(b) Zn + 2AgNO3 = Zn(NO3)2 + 2Ag
(c) 2Al + 3CuCl2 = 2AlCl3 + 3Cu
(d) BaCl2 + K2SO4 = BaSO4 + 2KCl
Q.8.
Ans:-
(a) 2KBr + BaI2 = KI + BaBr2
This is a double displacement reaction.
(b) ZnCO3 = ZnO + CO2
This is a decomposition reaction.
(c) H2 + Cl2 = 2HCl
This is a combination reaction.
(d) Mg + 2HCl = MgCl2 + H2
This is a displacement reaction.
Q.9. Ans:-
Those reaction in which heat is evolved (or produced) are known as exothermic reaction. for example,
C + O2 = CO2 + Heat
Those reaction reaction in which heat is absorbed (or participate) are known as endothermic reaction.
CaCO3 + Heat = CaO + CO2
Q.10. Ans:-
Respiration is considered an exothermic reaction because as we know that exothermic reaction produce heat and energy during chemical change. so during respiration, glucose combines with oxygen in the cells of our body to form carbon dioxide and water with the production of lot of heat and energy.
C6H12O6(glucose) + O2 = CO2 + H2O + Energy
Q.11.Ans:-
Decomposition reaction called the opposite of combination reaction because in decomposition reaction generally one compound split into two or more compound, but in Combination reaction generally two compound combined and a single compound formed. for example,
CaCO3 = CaO + CO2 this is decomposition reaction
CaO + CO2 = CaCO3 this is combination reaction.
Q.12. Ans:-
(a) CaCO3(s) ⟶ CaO(s) + CO2(g)
In this reaction energy is supplied in the form of heat.
(b) 2AgCl(s) ⟶ 2Ag(s) + Cl2(g)
in this reaction energy is supplied in the form of sunlight.
(c) 2H2O(L) ⟶ 2H2(g) + O2(g)
In this reaction energy is supplied in the form of electricity.
Q.13. Ans:-
In displacement reaction a more reactive metal displace a less reactive metal from its solution. on the other hand In double displacement reaction two compound exchange their ions to form two new compounds.
CuSO4 + Zn ⟶ ZnSO4 + Cu
here Zn is more reactive than copper so Zn displace copper from its solution CuSO4. so this reaction called displacement reaction.
Na2SO4 + HCl ⟶ NaCl + H2SO4
here sodium sulphate and hydrochloric acid combine together and exchange their electron to form sodium chloride and hydrogen sulphate. so this reaction called double displacement reaction.
Q.14. Ans:-
2AgNO3(aq) + Cu(s) ⟶ Cu(NO3)2(aq) + 2Ag(s)
silver nitrate copper copper nitrate silver
Q.15. Ans:-
Any reaction in which an insoluble solid (called precipitate) is formed that separates from the solution, is called precipitation reaction.
AgNO3(aq) + NaCl(aq) ⟶ AgCl(s) + NaNO3(aq)
Q.16. Ans:-
(a) Oxidation:- Gain of oxygen and loss of hydrogen is called Oxidation.
2Mg + O2 ⟶ 2MgO
CuO + H2 ⟶ Cu + H2O
(b) Reduction:- gain of hydrogen and loss of Oxygen.
ZnO + C ⟶ Zn + CO
Fe2O3 + 2Al ⟶ Al2O3 + 2Fe
Q.17. Ans:-
The shiny brown coloured element X is copper metal(Cu)
The black coloured compund formed is copper oxide.
Q.18. Ans:-
We apply paint on iron articles because paint prevent iron from rusting. this explains as follows when paint applied on iron then a thin layer of coated formed on iron surface due to this air and moisture cannot come in contact with the iron metal and hence no rusting takes place.
Q.19. Ans:-
The plastic bags containing oil and fat containing food items (such as potato chips) are flushed with an unreactive gas nitrogen so as to prevent them from getting oxidised and turn rancid. this is because in the presence of oxygen of air, the fats and oils prevent itms get oxidised forming products having unpleasant smell and taste.
Q.20. Ans:-
(a) Corrosion:- The process in which metals are eaten gradually by the action of air and moisture is called corroison.
(b) Rancidity:- The condition produced by oxidation of fats and oils in foods marked by unpleasant smell and taste is called rancidity. oil and fat containing food items (such as potato chips) are flushed with an unreactive gas nitrogen so as to prevent them from getting oxidised and turn rancid. this is because in the presence of oxygen of air, the fats and oils prevent itms get oxidised forming products having unpleasant smell and test.
