CBSE Class 10 Science Chemical Reactions and Equations MCQs Set C

Question : Lead nitrate Pb(NO₃)₂ on heating forms Lead oxide (PbO) solid and Nitrogen dioxide gas. What are the color of lead oxide and nitrogen dioxide?
(a) White, Colourless
(b) White, Brown
(c) Yellow, Brown
(d) Yellow, Colourless

Answer :  C

Question : One of the following is an endothermic reaction. This is
(a) Combination of carbon and oxygen to form carbon monoxide
(b) Combination of nitrogen and oxygen to form nitrogen monoxide
(c) Combination of glucose and oxygen to form carbon dioxide and water.
(d) Combination of zinc and hydrochloric acid to form zinc chloride and hydrogen

Answer :  B

Question : 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

Answer :  A

Question : Ethane (C₂H₆) on complete combustion gave CO₂ and water. It shows that the results are in accordance with the law of conservation of mass. Then, the coefficient of oxygen is equal to
(a) 3
(b) 5/2
(c) 2
(d) 7/2

Answer :  D

Question :  The process of reduction involves
(a) addition of oxygen
(b) addition of hydrogen
(c) removal of oxygen
(d) removal of hydrogen

Answer :  B

Question : Name the products formed when iron filings are heated with dilute hydrochloric acid
(a) Fe (III) chloride and water
(b) Fe (II) chloride and water
(c) Fe (II) chloride and hydrogen gas
(d) Fe (III) chloride and hydrogen gas

Answer :  D

Question : Assertion: Zinc reacts with sulphuric acid to form zinc sulphate and hydrogen gas and it is displacement reaction.
Reason: Zinc reacts with oxygen to form zinc oxide.
(a) Both A and R are true and R is the correct explanation of (a)
(b) Both A and R are true but R is not the correct explanation of (a)
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.

Answer :  B

Question : A reaction of hydrogen with oxygen to form water is a
(a) Endothermic reaction
(b) Exothermic reaction
(c) Decomposition reaction
(d) Reaction not feasible

Answer :  B

Question :  What is observed when a solution of potassium iodide is added to silver nitrate solution?
(a) No reaction takes place
(b) White precipitate of silver iodide is formed
(c) yellow precipitate of Agl is formed
(d) Agl is soluble in water.

Answer :  C

Question : Magnesium ribbon is cleaned before burning. Why?
(a) It absorbs moisture from the atmosphere which interferes with burning.
(b) It’s outer layer form oxides which interfere with burning.
(c) Dust from the atmosphere prevents its burning.
(d) All of the above

Answer :  B

Question : 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

Answer :  A

Question : The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called:
(a) antioxidation
(b) reduction
(c) rancidity
(d) corrosion

Answer :  C

Question : To facilitate the electrolysis of water we add a few drops of acids like sulfuric acid or salts like NaCl. Because:
(a) It acts as a catalyst
(b) It prevents the decomposition of electrodes used.
(c) It increases the electrical conductivity of water.
(d) None

Answer :  C

Question : Silver article turns black when kept in the open for a few days due to formation of
(a) H₂S
(b) AgS
(c) AgSO₄
(d) Ag₂S

Answer : D

Question : Which of the following does not involve a chemical reaction?
(a) Digestion of food in our body
(b) Process of respiration
(c) Burning of candle wax when heated
(d) Melting of candle wax on heating

Answer : D

Question : When Ag is exposed to air it gets a black coating of
(a) AgNO₃
(b) Ag2S
(c) Ag2O
(d) Ag2CO₃

Answer : B

Fill in the Blanks :

Question. The addition of oxygen to a substance is called …………. whereas removal of oxygen is called …………. . 
Answer : oxidation, reduction

Question. A balanced chemical equation has equal masses of various elements in ___________ and ___________ .
Answer : reactants, products

Question. Reaction in which an element displaces another element from its compound is called …………. .
Answer : displacement reaction

Question. Two antioxidants which are usually added to fat and oil containing foods to prevent rancidity, are …………., …………. .
Answer : BHA and BHT

Question…………. is the process in which metals are eaten up gradually by the action of air, moisture or a chemical on their surface.
Answer : Corrosion

Question. is an example of ___________ reaction.
Answer : decomposition

Question. The addition of hydrogen to a substance is called …………. whereas removal of hydrogen is called …………. .
Answer : reduction, oxidation

Question. Precipitation reactions produce insoluble …………. .
Answer : salts

Question. Reactions in which energy is given out are known as …………. .
Answer : exothermic reactions

Question. The colour of FeSO₄ crystal before ___________ heating is and after heating is ___________ .
Answer :  green, reddish brown

Question. SO₂ + 2H₂S → 2H₂O + 3S; SO₂ is ___________ acting as agent.
Answer : oxidising

Question. 2 FeSO₄ → Fe₂O₃ + SO₂ + ………….
Answer : SO₃

Question. Na₂SO₄ + BaCl₂ → …………. + 2NaCl
Answer : BaSO₄

Question. Complete the missing components/variables given as x and y in the following reactions:
(a) Pb (NO₃)₂ (aq) + 2KI (aq) → Pbl₂ (x) + 2KNO₃ (y)
(b) Cu (s) + 2AgNO₃ (aq) → Cu (NO₃)₂ (aq) + x (s)
Answer : (a) x → (s); y → (aq); (b) x → 2Ag

Question. The reaction Cu + xHNO₃ (cone.) → Cu(NO₃)₂ + yNO₂ + zH₂O The values of x, y and z are ___________ , ___________ and ___________ .
Answer : 4, 2 and 2

True Or False :

Question. In H2S + Cl2 → 2HCl + S, Cl2 is oxidising agent and H2S is reducing agent. 
Answer : True

Question. CaO + 2HCl → CaCl2 + H2O is neutralisation reaction. 
Answer : True

Question. Chemical reactions are those processes where new substances with old properties are formed. 
Answer : False

Question. All combustion reactions are oxidation reactions. 
Answer : True

Question. Displacement reaction can be redox reaction also. 
Answer : True

Question : Redox reactions are those where ___ simultaneously.
(a) exothermic - endothermic reactions occur
(b) oxidation - reduction occur
(c) reversible - irreversible reactions occur
(d) composition - decomposition reactions occur

Answer : B

Question : Redox reactions are useful in
(a) bleaching industry
(b) extraction of metals
(c) dying industry
(d) all of these

Answer : B

Question : In a chemical reaction, if one of the product is a gas which burns with a ‘pop’, then the gas is
(a) Cl₂
(b) O₂
(c) H₂
(d) CO₂

Answer : C

Question : The gas which turns lime water milky is
(a) SO
(b) CO
(c) CO₂
(d) H₂S

Answer : C

Question : The gas which has a characteristic pungent smell is
(a) NH₃
(b) Cl₂
(c) SO₂
(d) H₂

Answer : A

Question : The gas which smells like rotten eggs is
(a) CO₂
(b) NO₂
(c) SO₂
(d) H₂S

Answer : D

Question : The formation of gas bubbles in a liquid during a reaction is called
(a) fuzzing
(b) bubbling
(c) deliquidizing
(d) effervescence

Answer : D

Question : CuSO₄ + Fe ® FeSO₄ + Cu. During this reaction change of colour occurs as
(a) blue to pale green
(b) blue to black
(c) white to blue
(d) white to black

Answer : B

Question : Pb(NO₃)² which is colourless, reacts with H₂S to give a precipitate of PbS, whose colour is
(a) brown
(b) white
(c) black
(d) green

Answer : C

Question : In the electrolysis of water, liquid water decomposes into its
(a) two gaseous constituents
(b) one gaseous and one liquid constituent
(c) two liquid constituents
(d) two solid constituents

Answer : A

Question : H₂S + Cl₂ ® 2HCI + S In the above reaction, the gaseous reactants produce
(a) two solid products
(b) one gaseous and one solid product
(c) one liquid and one solid product
(d) one gaseous and one liquid product

Answer : B

Question : Solubility of a solute
(a) increases with temperature
(b) decreases with temperature
(c) remains constant
(d) none of these

Answer : A

Question : 4Fe + 3O₂ ¾¾®2Fe₂O₃ This reaction is
(a) moderate
(b) very fast
(c) very slow
(d) instantaneous

Answer : C

Question : Complete the reaction 2 Mg + 2H O¾¾®?
(a) Mg + 2H₂O
(b) Mg + H₂ + O₂
(c) MgO + H₂
(d) Mg(OH)₂+ H₂

Answer : D

Question : When Mg ribbon is dipped in a test tube containing conc. HCI, products formed are
(a) Mg + H₂ + Cl₂
(b) MgCl₂ + H₂
(c) Mg + Cl₂
(d) Mg+ H₂

Answer : B

Question : Which of the following is the fastest reaction?
(a) aluminium foil + NaOH + heat
(b) aluminium foil + NaOH
(c) aluminium powder + NaOH
(d) all the above

Answer : C

Question : Reaction in which heat energy is released is called
(a) irreversible
(b) reversible
(c) endothermic
(d) exothermic

Answer : D

Question : A catalyst when added to a chemical reaction changes the
(a) colour of the reactants
(b) course of the reaction
(c) speed of the reaction
(d) physical state of the products

Answer : C

Question : During the process of photosynthesis the catalyst is
(a) sunlight
(b) chlorophyll
(c) CO₂
(d) glucose

Answer : B

Question : In our body the catalyst which helps to break down food is
(a) dil HCI
(b) hormones
(c) NaOH
(d) digestive enzymes

Answer : D

Question : Which of the following is a reversible reaction?
(a) CaCO₃ + 2HCI ® CaCl₂ + CO₂+H₂O
(b) 2Mg + O₂® 2MgO
(c) N₂ + 3H₂ ® 2NH₃
(d) Fe + CuSO₄ ® FeSO₄ + Cu

Answer : C

Question : An example of exothermic reaction is
(a) CaO + H₂O ® Ca(OH)²
 (b) CaCO₃ ® CaO + CO₂
(c) 4Fe + 3O₂ ® 2Fe₂O₃
(d) 2Mg + O₂ ® 2MgO

Answer : A

Question : During photosynthesis, CO₂ reacts with H₂O to form glucose. The energy required for the reaction is obtained
(a) by heating
(b) from sunlight
(c) from electric current
(d) from CO₂

Answer : B

Question : In the decomposition of NH₄CI, the products formed are
(a) N₂ + Cl₂
(b) NH₃ + HCI
(c) H₂ + Cl₂
(d) N₂ + HCI

Answer : B

Question : Water breaks into its constituents
(a) by magnetic effect
(b) by light
(c) by heating
(d) by passing electric current

Answer : C