CBSE Class 10 Science Term 1 MCQ Sample Question Bank 2021-22

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Chemical Substances‐ Nature and Behavior

CH.1‐CHEMICAL REACTIONS AND EQUATIONS

1. Single Response Questions

Q1. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysisofwateris

(a)1:1    (b)2:1

(c)4:1    (d)1:2

Q2. Which among the following is (are) double displacement reaction(s)?

(t) Pb + CuCl → PbCl2 + Cu

2. Na2SO4 + BaCl2 → BaSO4 +2NaCl
3. C + O2 → CO2
4. CH4 + 2O2 → CO2 +2H2O

1. (i) and(iv)
2. (ii) only
3. (i) and(ii)
4. (iii) and(iv)

Q3 Which option denotes a double displacement reaction?

1. A + B + C
2. A + B → C
3. AC + BD → AD + BC
4. AC + B → AB + C

Q4 Which of the following is correct balanced equation:-

1. Fe + H₂O → Fe₃O₄ + H₂↑

b)2Fe+4H₂O→Fe₃O₄+4H₂↑

c) 3Fe+4H₂O→Fe₃O₄+4H₂↑

d) 3Fe+ H₂O→Fe₃O₄+ H₂↑

Q5.Areactioninwhichasingleproductisformedfromtwoormorereactantsisknownasa

………………….reaction.

a)combination    b) doubledisplacement

c)decompositionreaction    d) displacementreaction Q6.

Whatischemical formulafor marble?

a)CaO    b)Ca(OH)2    c)CaCO3    d)CaCl2 Q7. What is the chemical formula for quick lime?

a)CaO    b)Ca(OH)2    c)CaCO3    d)CaCl2 Q8.Whatisobservedwhenasolutionofpotassiumiodideisaddedtosilvernitratesolution?

1. Noreactiontakesplace
2. Whiteprecipitate ofsilveriodide is formed
3. yellow precipitate of Agl is formed
4. Aglissoluble in water.

Q9.Thefollowingreactionisanexampleofa 4NH3(g)+5O2(g)→4NO(g)+6H2O(g)

(i)displacementreaction    (ii) combinationreaction

(iii)redoxreaction    (iv) neutralisationreaction

CHEMICALREACTIONS ANDEQUATIONS

a) (i) and (iv)

2. (ii) and(iii)
3. (i) and(iii)
4. (iii) and(iv

Q10. Which of the following reactions is not correct:

1. Zn+ CuSO4 → ZnSO4 + Cu
2. 2Ag +Cu(NO3)2 → 2AgNO3 +Cu
3. Fe+CuSO4 →FeSO4 +Cu
4. Mg + 2HCl → MgCl2 +H2 Q11.Ifasubstancelosesoxygenorgainshydrogenduringareactionitissaidtobe………………

a)Oxidised    b)Reduced    c)tarnished    d) corroded

Q12. Some metals tarnished by substances around them such as moisture when left for some time whatisthisprocess called as?

a)Corrosion    b) Rancidity

c)Galvanization    d) Reduction Q13. Respiration isa /an:

1. endothermic reaction
2. exothermic reaction
3. decomposition reaction
4. displacement reaction

Q14. Keeping food in airtight containers helps to slow down:

1. reduction
2. displacement
3. oxidation
4. all of the above Q15.Whenasinglereactantbreaksdowntogivesimplerproductsthereactionisknownas:

1. endothermic reaction
2. exothermic reaction

c )decomposition reaction

d) oxidation reaction

2. Multiple Response Questions

Q1. Which among the following is an exothermic reaction?

1. respiration
2. decomposition ofvegetables
3. burningof natural gas
4. decomposition of silver chloride

Q2 Identify combination reactions given below:

CHEMICALREACTIONS ANDEQUATIONS

1. heatingof ferrous sulphate
2. reactionofquicklime with water
3. burning ofcoal
4. formationofwaterfromhydrogenandoxygen

Q3 Which among the following is/are chemical reactions?

1. souring ofmilk
2. cutting ofwood
3. cooking offood
4. burning

Q4 Identify endothermic reactions given below:

1. respiration
2. photosynthesis
3. melting of ice cube
4. reaction of silver bromide in sunlight. Q5 Howcanwepreventrancidity?

1. Addingantioxidants
2. Storingfoodinairtight containers
3. Replacing oxygeninthecontainerswithanother gas.
4. Its not possibletoprevent rancidity.

Followingquestionsconsistoftwostatements–Assertion(A)andReason(R).Answerthese questions selecting the appropriate option given below:

1. Both Aand Raretrueand Risthecorrectexplanation of A.
2. Both Aand Raretruebut Ris not thecorrectexplanationof A.
3. Aistrue but Ris false.
4. Ais false but Ristrue.

Q1Assertion (A):Calciumhydroxidewhenreactswithcarbondioxidegivescalciumcarbonateand   water.

Reason (R) : On heating calcium carbonate, decomposition reaction takes place.

Q2 Assertion (A):Decompositionofvegetablematterintocompostisanexampleofexothermic reactions.

Reason (R) : Exothermic reaction are those reactions in which heat is absorbed.

Q3 Assertion (A) : Green fumes are produced when lead nitrate is heated.

Reason (R) :Nitrogendioxidegasisproducedasabyproductduetothedecompositionoflead   nitrate.

CHEMICALREACTIONS ANDEQUATIONS

Q4 Assertion(A): When copper powder heated it becomes black in colour .

Reason(R): Copper oxide is produced due to oxidation which is black in colour.

Q5 Assertion (A):Chipsmanufacturersusuallyflushbagsofchipswithgassuchasnitrogento prevent the chips fromgettingoxidised.

Reason (R): Nitrogen being antioxidant prevents the chips from being oxidised.

1. CCT Questions

Q1

A student has been collecting antique silver utensils for her research. One day she observed a black coatingonsilver utensils.Whichchemicalphenomenonisresponsibleforthischange?Writethe chemical name ofblackcoating.

Q2 Whenanironnailisdippedincoppersulphatesolution,abrowncoatingofcopperisformedonthe surfaceofironand thecolourofcoppersulphatesolutionchangesfrombluetolightgreen.

Whydoesthecolourofcoppersulphatechangewhenanironnailiskeptinit?Justifyyouranswer.

Q3 Adarkroomisusedtoprocessphotographicfilm,tomakeprintsandtocarryoutother associatedtasks.Itisa roomthatcanbemadecompletelydarktoallowtheprocessingofthelight- sensitive photographic materials, including film and photographic paper. Silver bromide is a light- sensitivecompoundthatisitgetsdecomposedwhenexposed tolight.Sowhensilverbromideis exposedtosunlight,itgetsdecomposedtogivesilvermetalandbrominegasis liberated.The reactioniscalledaphotolysis reaction.

1. Duringdecompositionreactions……….isrequired.
2. Reactionsinwhichenergyisabsorbedareknownas…    reactions

Q4 Rashiwhitewashedherhome.Sheusedawhitepowderforwhitewashing. Itproducescalcium hydroxide(CaOH)2 whenitreactswithwater(H2O)andabsorbscarbondioxide(CO2)fromthe

CHEMICALREACTIONS ANDEQUATIONS

environment, as a result, it produces calcium carbonate (CaCO3) which creates a hard coating on the wallsand after 2-3 daysthe wallsstartshining.

1. Whichisslaked lime inabove reaction?
2. Whyisslaked lime isused forwhite washing?
3. AsolutionofasubstanceXisusedforwhitewashing.(1)NamethesubstanceXandwriteits formula.(2)Write thereactionofthesubstanceXnamedin(1)abovewithwater.
4. Why wallsstart shining after 2-3 days?

.

Answer‐Key CH.1‐CHEMICAL REACTIONS AND EQUATIONS

1. Single Response Questions

1.b (2Hydrogenand1oxygen)    2. B (Both reactants undergo displacement)    3.C    4.c    5. A

6.C    7.A        8.b(Whiteprecipitateofsilveriodideisformed)        9.C(DisplacementandRedox reaction)    10.a(Applyruleforbalancingchemicalequation)    11. B(Reduction is loss of Oxygen or gain of Hydrogen)

12. a (Itisaslowprocess)        13. Ansb- Exothermic reaction 14.Ansc–oxidation    15. Ansc– decomposition reaction

2. Multiple Response Questions:
3. Ans1 – options(a)(b) and(c)

Explanation: In exothermic reaction heat/energy is resleased

2. Ans2 -Options (b),(c) and(d)

Explanation: In combination reaction two or more reactants combine to form a product.

3. Ans3 – Options (a), (c) and (d)

Explanation: Chemical changes occur in chemical reactions.

4. Ans 4-Options (b), (c) and (d)

Explanation: In endothermic reaction energy is absorbed.

5. Ans5 – Options (a), (b) and (c)

Explanation: Rancidity can be prevented by slowing down oxidation of food containing fats and oils. (C) Assertion‐ Reason questions

1. b 2.c

3. d
4. a 5.a
5. CCT Questions

Ans1.The phenomenon is called corrosion (oxidation). Blackcoating onsilverutensilsissilversulphide.

2 Ag(s) + H2S(g) —> Ag2S(s) + H2(g)

silver sulphide

Ans2.Whenanironnailimmersedinthesolutionofcoppersulphatethanirondisplacescopperfrom the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.

Reaction:CuSO4(aq)+Fe(s)→FeSO4(aq)+Cu(s) Ans3.

1. energy b) endothermic Ans4. a) Ca(OH)2 calcium hydroxide
2. White-wash is especially compatible with masonry because it is absorbed easily and the resultant chemicalreaction hardensthe medium.

c)(1)The solution of the substance used for whitewashing is calcium oxide also called quicklime with chemical formula CaO.

2. Itformsslackedlimeorcalciumhydroxidewhenthequicklimereactswithwater CaO(s) +H2O

(l) → Ca(OH)2(aq).

d)Quicklime is used for whitewashing as it produces calcium hydroxide (CaOH) when it reacts with water(H2O)and absorbscarbondioxide(CO2)fromtheenvironment,asaresult,itproduces  calcium carbonate (CaCO3) which creates a hard coating on the walls. Walls start shining due to the formationofcalcium carbonate.