NCERT Exemplar Solution Class 10 Science Chapter 1
NCERT Exemplar Solution Class 10 Science Chapter 1 Chemical Reactions and Equations all Questions Answer Solution. NCERT Exemplar Class 10 Science Chapter 1 Solution PDF.
NCERT Exemplar Solution Class 10 Science Chapter 1: Overview
NCERT Exemplar Solution Class 10 Science Chapter 1 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
10 |
Subject |
Science |
Chapter |
1 |
Chapter Name |
Chemical Reactions and Equations |
NCERT Exemplar Solution Class 10 Science Chapter 1 Chemical Reactions and Equations
Multiple Choice Questions
1) Which of the following is not a physical change?
a) Boiling of water to give water vapour
b) Melting of ice to give water
c) Dissolution of salt in water
d) Combustion of liquefied petroleum Gas (LPG)
Answer:- d) Combustion of liquefied petroleum Gas (LPG)
Explanation: Combustion is not the physical change. It is a chemical change and there is formation of new of compound after burning of LPG.
2) The following reaction is an example of a
4NH3 (g) + 5O2(g) → 4NO (g)+6H2O (g)
I) Displacement reaction
II) Combustion reaction
III) Redox reaction
IV) Neutralisation reaction
a) I) and IV)
b) II) and III)
c) I) and III)
d) III) and IV)
Answer:- c) I) and III)
Explanation: The given reaction is the example of Displacement reaction and Redox reaction. Redox reaction is the simultaneous oxidation and reduction reaction. And there is Displacement of oxygen at the place of hydrogen.
3) Which of the following statements about the given reaction are correct ?
3Fe(s) + 4H2O(g) → Fe3O4 + 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, II, and III
b) III, and IV
c) I, II, and IV
d) II, and IV
Answer:-c) I, II, and IV
Explanation: In these reaction, iron is oxidised due to Combination of Water and Oxygen. Water is reduced due to removal of oxygen. Here oxidation and reduction occurs simultaneously. Hence Redox reaction is carried out there.
4) 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) III and IV
Answer:- a) I and II
Explanation: Reaction of water with quick lime and Dilution of an acid both are exothermic reaction. Because both reaction releases heat at the time of reaction.
5) Three beakers labelled as A, B and C each containing 25 ml of water were taken. A small amount of NaOH, anhydrous CuSO4 and NaCl were added to beakers A,B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statements (s) is (are) correct ?
I) In beakers A and B, exothermic process has occurred.
II) In beakers A and B, endothermic process has occurred.
III) In beaker C exothermic process has Occurred.
IV) In beaker C endothermic process has occurred.
a) I only
b) II only
c) I and IV
d) II and III
Answer:- c) I and IV
Explanation: In beakers A and B, exothermic process has occurred. Because exothermic reaction evolves heat and increase in temperature during the process. And In beaker C endothermic process has occurred because endothermic reaction decrease the temperature.
6) A dilute Ferrous sulphate solution was gradually added to the beaker containing acidified permanganate Solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation ?
a) KMnO4 is an oxidising agent , it oxidises FeSO4.
b) FeSO4 acts as an oxidising agent and oxidises KMnO4
c) The colour disappears due to dilution; no reaction is involved
d) KMnO4 is an unstable compound and decomposes in presence of FeSO4 to a colourless compound.
Answer:- a) KMnO4 is an oxidising agent , it oxidises FeSO4.
Explanation: KMNO4 is potassium permanganate us strong oxidising agent. The dark purple colour solution occurs on addition of KMnO4. But when reaction occurs it oxidises FeSO4 and thus the Colour fades and finally disappears.
7) Which among the following is ( are ) double displacement reactions ?
i) Pb+ Cucl2 → pbCl2 + Cu
ii) Na2SO4 + BaCl2 → BaSo4+ 2NaCl
iii) C + O2 → CO2
iv) CH4 + 2O2 → CO2 + 2H2O
a) I and IV
b) II only
c) I and II
d) III and IV
Answer:- b) II only
Na2SO4 + BaCl2 → BaSo4 + 2NaCl
Explanation: These is the double displacement reaction where Barium is displaced by the sodium and sodium is displaced by the barium.
8) Which among the following statement(s) is (are) true? Exposure of silver Chloride to sunlight for a long duration turns grey due to
i) The formation of silver by decomposition of silver Chloride
ii) Sublimation of silver Chloride
iii) Decomposition of Chlorine gas from silver Chloride
iv) Oxidation of silver Chloride
a) I only
b) I and III
c) II and III
d) IV only
Answer:- a) I only
Explanation: The formation of silver by decomposition of silver Chloride. Is the true statement. Because the Decomposition reaction occurs there.
9) Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by liberation of heat. This process is called slaking of limewater. Which among the following is (are) true about slaking of lime and the solution formed ?
i) It is an endothermic reaction
ii) It is an exothermic reaction
iii) The pH of the resulting solution will be more than seven
iv) The pH of the resulting solution will be less than seven
a) I and II
b) II and III
c) I and IV
d) III and IV
Answer:- b) II and III
Explanation: It is an exothermic reaction and The pH of the resulting solution will be more than seven these two statements are true about slaking of lime.
The exothermic reaction increases the heat of mixture and the pH will be more than 7 thus the mixture will be alkaline in nature.
10) Barium Chloride on reacting with Ammonium Sulphate forms barium Sulphate and Ammonium Chloride. Which of the following correctly represents the type of the reaction involved?
I) Displacement reaction
II) Precipitation reaction
III) Combustion reaction
IV) Double displacement reaction
a) I only
b) II only
c) IV only
d) II and IV
Answer:- d) II and IV
Precipitation reaction and Double displacement reaction
Explanation: Ammonium and Barium both displace each other from their salts. Thus double displacement reaction occurs. And there is formation of precipitate.
11) Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is
a) 1:1
b) 2:1
c) 4:1
d) 1:2
Answer:- b) 2:1
Explanation: The mole ratio between the hydrogen and oxygen is 2:1 because there is 2 mole of Hydrogen and 1 mole of oxygen in the water.
12) Which of the following is (are) an endothermic process (es) ?
I) Dilution of sulphuric acid
II) Sublimation of dry ice
III) Condensation if water vapours
IV) Evaporation of water
a) I and III
b) II only
c) III only
d) II and IV
Answer:- d) II and IV
Explanation: Sublimation of dry ice and Evaporation of water are exothermic process . Both the process decreasetemperature during the process. While the other two reaction are exothermic in nature. Which evolves heat during process and increase temperature.
13) In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity of lead nitrate is not available, which of the following can be used in place of lead nitrate?
a) Lead sulphate ( insoluble)
b) Lead acetate
c) Ammonium nitrate
d) Potassium sulphate
Answer:- b) Lead acetate
Explanation: At the place of lead nitrate, lead acetate can be used. Then after performing the double displacement reaction and forms the product of lead iodide with yellow precipitate.
14) Which of the following gases can be used for storage of fresh sample of an oil for a long time?
a) Carbon dioxide or oxygen
b) Nitrogen or oxygen
c) Carbon dioxide or helium
d) Helium or nitrogen
Answer:- d) Helium or nitrogen
Explanation: Helium and nitrogen both can be used as an oxidising agent. As these are less reactive these does keeps the oil fresh for longer time.
15) The following reaction is used for the preparation of oxygen gas in the laboratory
Which of the following statement(s) is (are) correct about the reaction?
a) It is a decomposition reaction and endothermic in nature
b) It is a combination reaction
c) It is a decomposition reaction and accompanied by release of heat
d) It is a photochemical decomposition Reaction and exothermic in nature.
Answer:- a) It is a decomposition reaction and endothermic in nature
Explanation: In the given reaction decomposition of potassium chlorate. Which further gives potassium chloride and oxygen . Also the endothermic reaction occurs i.e. the decrease in the temperature during the reaction.
16) Which one of the following processes involve chemical reactions ?
a) Storing of oxygen gas under pressure in a gas cylinder
b) Liquefaction of air
c) Keeping petrol in a china dish in the open
d) Heating copper wire in presence of air at high temperature
Answer:- d) Heating copper wire in presence of air at high temperature
Explanation: Heating of copper wire in the presence of high temperature leads to the chemical reaction which is oxidation. But other does not lead to any chemical reaction.
17) In which of the following chemical equations, the abbreviations represents the correct states of the reactions and products involved at reaction temperature ?
a) 2H2(I) + O2 (I) → 2H2O (g)
b) 2H2(g) + O2 (I) → 2H2O (I)
c) 2H2 (g) + O2(g) → 2H2O (I)
d) 2H2(g) + O2(g) → 2H2O(g)
Answer:- c) 2H2 (g) + O2(g) → 2H2O (I)
Explanation: Option C has correct abbreviations. Because hydrogen and oxygen are gas in nature but when it combines to form the water i.e. H2O then it is liquid in nature. Hence c is correct.
18) Which of the following are combination reactions ?
∆
i) 2KClO3 –→ 2KCl + 3O2
ii) MgO + H2O → Mg(OH)2
iii) 4Al +3O2 → 2Al2O3
iv) Zn + FeSO4 → ZnSO4 + Fe
a) I and III
b) III and IV
c) II and IV
d) II and III
Answer:- d) II and III
MgO + H2O → Mg(OH)2and
4Al +3O2 → 2Al2O3 both the reactions are combination reactions.
Explanation: Because in both the Reaction two reactants combine to form single product hence both the reactions are combination reactions.
Short Answer Questions
19) Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
a) Nitrogen gas is treated with hydrogen gas in the presence of a catalyst at 773k to form ammonia gas.
Answer:-
The given reaction is Combination reaction.
The balanced chemical equation of the given reaction is
Catalyst
N2(g) + 3H2(g) ————-→ 2NH3 (g)
773 K
b) Sodium hydroxide solution is treated with acetic acid to form sodium acetate and water.
Answer:-
The given reaction is Double displacement reaction, and it is also known as Neutralisation reaction.
It is represented as –
NaOH (aq) + CH3COOH(aq) → CH3COONa (aq) + H2O (I)
c) Ethanol is warmed with ethanoic acid to form ethyl acetate in the presence of concentrated H2SO4
Answer:-
The given reaction is Double displacement reaction.
It is represented as –
H +
C2H5OH (I) + CH3COOH(l) ———–→ CH3COOC2H5(I) + H2O(I)
d) Ethane is burnt in the presence of oxygen to form Carbon dioxide, water and releases heat and light.
Answer:-
The given reaction is Redox reaction.
It is represented as –
C2H4(g) + 3O2 (g) → 2CO2(g) + 2H2O(g) + Heat + light
20) Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
a) Thermit reaction, iron (III) oxide reacts with aluminium and gives molten iron and aluminium oxide.
Answer:-
The given reaction is Displacement reaction.
It is represented as-
Fe2O3 (s) + 2Al(s) → Al2O3 (s) + 2Fe (I) + Heat
b) Magnesium ribbon is burnt in an atmosphere of nitrogen gas
Answer:-
The given reaction is Combination reaction
It is represented as –
3Mg(s) + N2 (g) → Mg3N2 (s)
c) Chlorine gas is passed in an aqueous potassium iodide solution to form potassium chloride solution and solid Iodine.
Answer:-
The given reaction is Displacement reaction.
It is represented as –
2KCl (aq) + Cl2(g) → 2KCl(aq) + I2(s)
d) Ethanol is burnt in air to form Carbon dioxide, water and releases heat.
Answer:-
The given reaction is Redox reaction.
This is represented as –
C2H5OH (I) + 3O2 (g) → 2CO2 (g) + 3H2O(I) + Heat
21) Complete the missing components/ variables given as x and y in the following reactions.
a) Pb(NO3)2 (aq) + 2Kl(aq) → pbI2 (x) + 2KNO3(y)
Answer:-
Here, x is (s) and y is (aq)
Pb(NO3)2 (aq) + 2Kl (aq) → pbI2 (s) + 2KNO3(aq)
b) Cu(s) + 2AgNO3 (aq) → Cu(NO3)2 (aq) + x(s)
Answer:-
Here, x is 2Ag
Cu(s) + 2AgNO3 (aq) → Cu(NO3)2 (aq) + 2Ag(s)
c) Zn(s) +H2SO4 (aq) → ZnSO4 (x) + H2(y)
Answer:-
Here x = (aq)
And y = (g)
Zn(s) +H2SO4 (aq) → ZnSO4 (aq) + H2(g)
x
d) CaCO3 (s) ––→ CaO(s) + CO2 (g)
Answer:-
Here x = Heat (∆)
∆
CaCO3 (s) ———–→CaO(s) + CO2 (g)
22) Which among the following changes are exothermic or endothermic in nature?
a) Decomposition of ferrous sulphate
Answer:- Endothermic change
b) Dilution of sulphuric acid
Answer:- Exothermic change
c) Dissolution of sodium hydroxide in water
Answer:- Exothermic change
d) Dissolution of ammonium chloride in water.
Answer:- Endothermic change
23) Identify the reducing agent in the following reactions.
a) 4NH3 + 5O2 → 4NO + 6H2O
Answer:- In these reaction the reducing agent is Ammonia i.e NH3
b) H2O + F2 → HF + HOF
Answer:- In these reaction the reducing agent is water (H2O).
c) Fe2O3 + 3CO → 2Fe + 3CO2
Answer:- In these reaction the reducing agent is Carbon Monoxide i.e. CO
d) 2H2 + O2 → 2H2O
Answer:- Here the reducing agent is H i.e Hydrogen.
24) Identify the oxidising agent (oxidant) in the following reactions
a) Pb3O4 + 8Hcl → 3pbCl2 + Cl2 + 4H2O
Answer:-
In these reaction the oxidising agent is Pb3O4.
b) 2Mg + O2 → 2MgO
Answer:- the oxidising agent is O2.
c) CuSO4 + Zn → Cu + ZnSO4
Answer:- the oxidising agent is CuSO4.
d) V2O5 + 5Ca → 2V + 5CaO
Answer:- In these reaction the oxidising agent is V2O5.
e) 3Fe + 4H2O → Fe3O4 + 4H2
Answer :- The Oxidising agent is H2O.
f) CuO + H2 → Cu + H2O
Answer:- The Oxidising agent is CuO.
25) Write the balanced equations for the following reactions
a) Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate
Answer:-
The representation of the chemical equation for the given reaction is
Na2CO3 + HCl → NaCl + NaHCO3
b) Sodium hydrogen carbonate on reaction with hydrochloric acid gives Sodium chloride, water and liberates Carbon dioxide.
Answer:-
The representation of the chemical equation for the given reaction is
NaHCO3 + HCl → NaCl + H2O + CO2
c) Copper sulphate on treatment with potassium iodide precipitates cuprous Iodide (Cu2I2), liberates Iodine gas and also forms potassium sulphate.
Answer:-
The representation of the chemical equation for the given reaction is
2CuSO4 + 4KI → Cu2I2 + 2K2SO4 + I2
26) A solution of potassium chloride when mixed with silver nitrate Solution, an insoluble white substances is formed. Write the chemical reaction involved and also mention the type of the chemical reaction?
Answer:-
The given reaction is the type of Double displacement reaction and Also precipitation reaction As white substances is formed in it.
The chemical equation Involved in these reaction is
KCl (aq) + AgNO3 (aq) → AgCl(s) + KNO3 (aq)
27) Ferrous sulphate decomposes with the evolution of a gas having a characteristic odour of burning sulphur. Write the chemical reaction involved and identify the type of reaction.
Answer:-
In these reaction ferrous sulphate is decomposed, with evolution of gas and odour of burning sulphur, Hence is the type of thermal decomposition reaction.
The chemical equation for the given reaction will be
∆
2FeSO4 (s) ———→ Fe2O3 (s) + SO2(g) + SO3 (g)
28) Why do fire flies glow at night ?
Answer:-
The fire flies glow at the night due to the emission of visible light. They produces an proteinous enzymes in their body which undergoes the chemical reaction when comes in contact with the oxygen. Here the chemical reaction occurs i.e. oxidation. As the light range is small thus it does not see in the days but at night it glows due to visible light.
29) Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented. Under what conditions do these grapes ferment?Is it a chemical or a physical change?
Answer:-
The grapes ferment is the chemical change. As the fermentation process lead to the chemical reaction in it. The change is chemical. When these grapes are attached to the branches of the plant the provides nutrients to it constantly and the grapes are thus living. The plants immune system prevent the grapes from fermenting, and the microbes does not over the grapes. But after plucking the grapes these are not living hence does not prevented by Immune system thus Microbes attack over it and it startsfermentation, under the anaerobic conditions.
30) Which among the following are physical or chemical changes ?
a) Evaporation of petrol
Answer:- it is a physical change.
There is no any chemical reaction Involved in the process thus it is a physical change from liquid to gaseous.
b) Burning of liquefied petroleum Gas (LPG)
Answer:- it is a chemical change.
The chemical reaction is involved in this process.
c) Heating of an iron rod to red hot.
Answer:- it is a physical change.
There is no any chemical reaction Involved hence it is physical change.
d) Curdling of milk
Answer:- it is a chemical change.
Chemical reaction is involved in the process.
e) Sublimation of solid Ammonium Chloride
Answer:- it is a physical change.
A physical change is done, from solid to the gaseous.
31) During the reaction of some metals with dilute hydrochloric acid, following observations were made.
Explain these observations giving suitable reasons.
a) Silver metal does not show any change.
Answer:- silver metal does not show any changes when dilute HCl is added to it because, it does not react with the HCl.
b) The temperature of the reaction mixture rises when aluminium (Al) is added.
Answer:-
When aluminium is mixed with the dil. HCl then the reaction occurs over there is exothermic reaction which rises the temperature of the mixture.
c) The reaction of sodium metal is found to be highly explosive
Answer:-
The reaction of sodium with Dil. HCl is vigorous reaction because it is an exothermic reaction hence highly explosive.
d) Some bubbles of a gas are seen when lead(pb) is reacted with the acid.
Answer:-
When lead reacted with Dil. HCl then the bubbles arises are of hydrogen gas. The reaction leads to the by product of H2.
32) A substance X, which is an oxide of a group 2 element, is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X also write the chemical reactions involved.
Answer:-
The substance X which is an oxide of group 2 element is Calcium Oxide. It is highly used in the cement industry also these is present in the bones. Hence it is Calcium Oxide. The chemical reaction Involved with the Calcium oxide with water leads to the formation of aqueous solution of Calcium hydroxide, Which turns the red litmus blue.
The reaction occurs as-
CaO (s) + H2O (I) → Ca(OH)2 (aq)
Calcium oxide Water Calcium hydroxide
33) Write a balanced chemical equations for each of the following reactions and also classify them.
a) Lead acetate Solution is treated with dilute hydrochloric acid to form lead Chloride and acetic acid solution.
Answer:-
The Reaction is Displacement reaction.
The equation for the Reaction is –
Pb(CH3COO)2 + 2HCl → PbCl2 + CH3COO
Lead acetate lead Acetic Chloride Acid
b) A piece of sodium metal is added to absolute ethanol to form sodium ethoxide and hydrogen gas .
Answer:-
The reaction occurs here is Displacement reaction.
The equation for the given reaction is –
2Na + 2C2H5OH → 2C2H5ONa + H2
Sodium Ethanol Sodium Ethoxide Hydrogen
c) Iron III oxide on heating with carbon monoxide gas reacts to form solid iron and liberates Carbon dioxide gas.
Answer:-
The Reaction occurs here is Redox reaction. Redox reaction is simultaneously occurring of oxidation and reduction reaction.
The equation for the given reaction is –
Fe2O3 + 3CO → 2Fe + 3CO2
Iron(III) oxide (Fe2O3) with carbon monoxide (CO) Iron (Fe) and carbon dioxide (CO2)
d) Hydrogen sulfide gas reacts with oxygen gas to form solid sulphur and liquid water.
Answer:-
The reaction carried out here is Redox reaction. In which simultaneous reduction and oxidation occurs.
The equation for the reaction is –
2H2S + O2 → 2S + 2H2O
Hydrogen Sulfide oxygen Sulphur water
34) Why do we store silver Chloride in dark coloured bottles?
Answer:- Silver Chloride is kept in dark coloured bottles because it undergoes chemical reaction when expose to the sunlight. The decomposition reaction takes place over there. Hence the silver Chloride can be decomposed if kept in open. The reaction carried out in the process is –
Sunlight
2AgCl —————→ 2Ag + Cl2
Silver Chloride Silver Chlorine
35) Balance the following chemical equations and identify the type of chemical reaction.
a) Mg(s) + Cl2(g) → MgCl2 (s)
Answer :-
The type of these chemical reaction is –
Combination reaction.
These is a balanced reaction.
∆
b) HgO(s) –––→ Hg (I) + O2(g)
Answer:-
These is a type of Decomposition reaction.
The balanced chemical equation is –
∆
2HgO(s) –––→ 2 Hg (I) + O2(g)
Fuse
c) Na(s) + S (s) ———→Na2S(s)
Answer:-
These is a type of combination reaction.
The balanced chemical equation is –
Fuse
2Na(s) + S (s) ———→Na2S(s)
d) TiCl4(I) + Mg(s) → Ti (s) + MgCl2 (s)
Answer:-
These reaction is the Displacement reaction.
The balanced chemical equation is –
TiCl4(I) + 2Mg(s) → Ti (s) + 2MgCl2 (s)
d) CaO (s) + SiO2(s) → CaSiO3 (S)
Answer:-
These reaction is Combination reaction.
And the reaction is balanced.
U.V
f) H2O2 (I) —–→ H2O(I) + O2 (g)
These reaction is Decomposition reaction.
The balanced chemical reaction is –
U.V
2 H2O2 (I) ————→ 2H2O(I) + O2 (g)
36) A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continuous to burn and forms a compound Y.
a) Write the chemical formulae of X and Y.
b) Write a balanced chemical equation, when X is dissolved in water.
Answer:-
A)
When the magnesium ribbon is burnt with the oxygen along with sunlight
Then the reaction occurs as
Sunlight
2Mg + O2 —————-→ 2MgO
Thus x is 2MgO.
And when the magnesium ribbon is burnt in nitrogen atmosphere then the reaction is
3Mg + N2 → Mg3N2
Thus the product y is Mg3N2.
B)
The balanced chemical equation when X i.e MgO magnesium oxide dissolved in water is
MgO + H2O → Mg(OH)2
37) Zinc liberates hydrogen gas when reacted with dilute hydrochloric acid, whereas copper does not. Explain why?
Answer:-
Zinc is more reactive than the Hydrogen and hydrogen is more reactive than copper thus the hydrogen liberates over zinc when zinc reacts with HCl but copper does not react. Because copper is below the hydrogen on the reactivity Series of metals.
38) A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
a) Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
Answer:-
The phenomenon beyond the turning black of the silver articles when kept in open is Corrosion.
The Corrosion occurs when the silver reacts with the moisture, gases or acids etc. The chemical reaction occurs and silver gets corrode these chemical reaction changes the colour into black.
b) Name the black substance formed and give its chemical formula.
Answer:-
The black substance formed after corrosion of silver is Silver Sulphide. chemical formula is Ag2S . It is thin coating formed after the silver corrodes. When the silver comes in constant with the moisture, then the corrosion reaction takes place.
Long Answer Questions
39) On heating blue coloured powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed.
a) Write a balanced chemical equation of the reaction.
Answer:-
The balanced chemical equation for the Given reaction is –
Heat
2Cu(NO3)2 (s) ————→ 2CuO (s) + O2(g) + 4 NO2 (g)
b) Identify the brown gas X evolved.
Answer:-
The brown gas Evolved during the chemical reaction is X – Nitrogen dioxide (NO2).
c) Identify the type of reaction.
Answer:- The given reaction is the type of Decomposition reaction.
d) What could be the pH range of aqueous solution of the Gas X?
Answer:- the gas X which is nitrogen dioxide ( NO2) is a oxide if non- metal. Thus it dissolves in water and gives acidic solution. And acids have the pH range below 7.
40) Give the characteristics tests for the following gases
a) CO2
Answer:-
The confirmation test for the CO2 is Let the CO2 gas pass through the limewater and if the water turns milky and precipitate formed in it then the CO2 gas is confirmed.
b) SO2
Answer:-
The confirmation test for the So2 gas is smell. The smell of the SO2 gas is so bad like an Rotten eggs. These confirms the So2.
c) O2
Answer:-
Oxygen supports the burning. Hence the confirmation test for O2 is burning of matchstick near the O2, if the stick burns with more brightness then O2 is confirmed.
d) H2
Answer:-
The confirmation test for the H2 gas is let the burning stick bring near the Gas and if there is pop up sound appears then the H2 gas confirmed.
41) What happens when a piece of following
Also, write the balanced chemical equation if the reaction occurs.
a) Zinc metal is added to copper sulphate solution ?
Answer:-
When a piece of Zinc metal is added to copper sulphate solution then the chemical reaction occurs which is displacement reaction. The zinc displace the copper. And it gives the product of zinc sulphate.
The equation for the chemical reaction is
Zn(s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)
b) Aluminium metal is added to dilute hydrochloric acid?
Answer:-
When aluminium metal is added to the dil. HCl the chemical reaction occurs and there is formation of aluminium chloride as product with the evolution of Hydrogen gas.
The equation for the chemical reaction is –
2Al (s) + 6 HCl (aq) → 2AlCl3(aq) + 3H2
c) Silver metal is added to copper sulphate solution?
Answer:-
No chemical reaction occurs when silver metal is added to copper sulphate solution because silver is Non- reactive metal, thus does not react with it thus there is no any reaction takes place.
42) What happens when zinc granules are treated with dilute solution of H2SO4, HCl, HNO3, NaCl, and NaOH, also write the chemical equations if reaction occurs.
Answer:-
When zinc granules are treated with the following dilute solution then –
1) H2SO4 –
When zinc granules are treated with Dil. H2SO4 the reaction occurs is displacement reaction.
Zn(s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g)
2) HCl –
When zinc granules are treated with Dil. HCl then reaction occurs as –
Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g)
3) HNO3 –
Nitric acid is strong oxidising agent hence the reaction carried out in it is –
4Zn (s) + 10HNO3 (aq) → 4Zn(NO3)2 (aq) + 5 H2O (I) + N2O (g)
4) NaCl–
When zinc reacts with Dil. NaCl solution then There is no any reaction occurs.
5) NaOH –
When zinc Reacts with Dil. NaOH the reaction is proceeds and it is as –
Zn (s) + 2 NaOH(aq) →Na2ZnO2(aq) + H2 (g)
43) On adding a drop of barium Chloride solution to an aqueous solution of sodium sulphate, white precipitate is obtained.
a) Write a balanced chemical equation of the reaction involved
Answer:- the balanced chemical equation for the given reaction is –
BaCl2 + Na2SO3 → BaSO3 + 2NaCl
b) What other name can be given to this precipitation reaction ?
Answer:-the precipitation reaction is also known as double displacement reaction.
c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears . Why?
Answer:- the reaction mixture Barium Chloride, when it reacts with the dil. HCl then Barium Chloride, Sulphur Dioxide and Water are formed as by product. The product barium Chloride forms the white precipitate Which is soluble in water.
The reaction is like –
BaSO3 + HCl → BaCl3 + SO2 + H2O
44) You are provided with two containers made up of copper and aluminium. You are provided with solutions of dilute HCl, dilute HNO3, ZnCl2 and H2O. In which of the above containers these Solutions can be kept?
Answer:-
a) HCl →
Dil. HCl can be kept in the container made up of copper because it does not react with copper. But when the HCl is kept in aluminium container it reacts with aluminium and it forms the salt and evolution of hydrogen gas. Thus, it cannot be kept with aluminium.
b) HNO3
If dil. HNO3 is kept in copper container then it reacts with it and thus it cannot kept in the copper container.
And if the dil. HNO3 is kept in the aluminium container then it also reacts with it and oxidation of aluminium takes place. Thus it cannot kept in aluminium container also.
c) ZnCl2
If Solution of ZnCl2 is kept in copper container then there is no any reaction occurs and hence it can kept in the copper container.
When it is kept in the aluminium container then there is occurrence of reaction. Because aluminium is more reactive than zinc hence displacement reaction occurs over there. Thus it cannot keep in the aluminium container.
d) H2O (water )
Water does not reacts with both of them not with aluminium also copper hence it can kept in both containers.