Q1
In Which Of The Following Statements Is Or Are Incorrect?
[A]. When calcium hydroxide solution lime water reacts with carbon dioxide gas a white precipitate of calcium carbonate is formed along with water.
[B]. When zinc metals react with dilute sulphuric acid to form zinc sulphate solution and hydrogen gas.
[C]. During respiration glucose combines with oxygen in the cells of our body to form carbon dioxide and water along with the production of energy.
[D]. The reaction between nitrogen and oxygen to form nitrogen monoxide is an an exothermic reaction.
Answer: Option D
Explanation:
The reaction between nitrogen and oxygen to form nitrogen monoxide is an endothermic reaction because heat is absorbed in this reaction. Actually, when nitrogen and oxygen are heated to a very high temperature about 3000 degree Celsius, they combined to form nitrogen monoxide and a lot of heat is absorbed in this reaction.

Q2
Nancy Is Writing Some Indicating Information About Chemical Equation. Choose The Correct One(S):
[A]. By indicating the physical state of the reactant and products.
[B]. By indicating the heat change take place in the reaction.
[C]. By indicating the condition under which their reaction takes place.
[D]. All the above.
Answer: Option D
Explanation:
Here are all the statements are correct. Hence, your answer will be option [D].

Q3
Which Of The Following Processes Involve Chemical Reactions?
[A]. A storing of oxygen gas under pressure in a gas cylinder.
[B]. Liquefaction of air.
[C]. Keeping petrol in china dish in an open.
[D]. Heating copper wire in the absence of air at high temperature.
Answer: Option D
Explanation:
During a chemical reaction the chemical composition of a substance changes. A chemical reaction produces a new substance with new properties. Energy is either released or absorbed during a chemical reaction. It is an irreversible reaction. You can easily understand by this equation: 2CU (copper wire) + O2 → 2CuO (copper oxide)

Q4
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 If 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: Option B
Explanation:
Lead sulphate being insoluble will not dissociate into Pb2+ ions.

Q5
Pooja Is Writing Some Statements. She Wants To Know In Which Of The Following Statements Is Or Are Incorrect?
[A]. When hydrogen burns in oxygen to form water.
[B]. Liquid hydrogen burns to lift the space shuttle out of the earth’s gravitational field.
[C]. When glucose undergoes to slow combustion by combining with oxygen in the cells of our body to produce energy.
[D]. As a fuel CNG and LPG gives more energy than hydrogen.
Answer: Option D
Explanation:
As a fuel hydrogen is more efficient then CNG and LPG. Hence, liquid hydrogen burns in liquid oxygen to form water providing a tremendous amount of energy to lift the space shuttle out of the earth’s gravitational field.

Q6
Consider The Following Statements, Choose The Incorrect One(S):
[A]. The chemical equation is balance to satisfy the law of conservation of mass in chemical reaction.
[B]. We should never change the formula of an element or compound to balance and equation.
[C]. Those reaction in which heat is evolved are known as exothermic reactions.
[D]. When Methane (CH4) burns in oxygen of air it forms carbon monoxide and water vapour.
Answer: Option D
Explanation:
When Methane (CH4) burns in oxygen of air it forms carbon dioxide and water vapour. Rest of all statements are correct. Hence, your answer will be option [D].

Q7
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: Option D
Explanation:
Helium or nitrogen both can be used for storage of fresh sample of an oil for a long time. These gases are called inert gases as they do not react with most elements including oxygen. Thus, these gases create an inert environment for the oil and prevent its reaction with any element in the environment that prevent from getting it stale.

Q8
Which Of The Following Is (Are) An Endothermic Process (Es)?
[A]. Dilution of sulphuric acid, and Condensation of water vapours.
[B]. Sublimation of dry ice.
[C]. Condensation of water vapours.
[D]. Sublimation of dry ice, and Evaporation of water
Answer: Option D
Explanation:
Sublimation of dry ice and evaporation of water both are endothermic processes. These processes pull heat (energy) from their surroundings to change from one state to another. Hence both these processes produce cooling rather than heating. Dry ice absorbs heat from the environment to convert into ga

Q9
Paheli Is Writing Some Statement Which Is Given By Her Teacher. Would You Help Him To Choose The Incorrect Statements?
[A]. The combustion reaction of candle wax is characterized by a change in state from solid to liquid and gas.
[B]. When a chemical reaction absorbs heat energy, then the temperature of reaction mixture is falls and it becomes cold.
[C]. When a Zinc metal reacts with dilute sulphuric acid to form zinc sulphate and hydrogen gas.
[D]. None of the above.
Answer: Option D
Explanation:
Here are all the statements are correct. Hence, your answer will be option [D].

Q10
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: Option B
Explanation:
The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is 2:1 by volume. In a decomposition reaction, a compound is broken down into its simpler forms. During electrolysis water is broken down into oxygen gas and hydrogen gas due to passing of electric current through it. You can easily understand by this equation: 2H2O (I) → 2H2(g) + O2(g) The mole ratio of hydrogen and oxygen gases is 2:1 by volume.

Q11
Boojho Appeared In Class Test Where He Wrote Some Statements But He Confused To Know The Correct Statement. Would You Help Him To Know That?
[A]. Some chemical reaction and are characterized by a change in colour.
[B]. The purple colour of potassium permanganate solution disappears when citric acid reacts with potassium permanganate solution.
[C]. The orange colour of potassium dichromate solution changes to green when sulphur dioxide gas is passed through acidified potassium dichromate solution.
[D]. All the above.
Answer: Option D
Explanation:
Here are all the statements are correct. Hence, your answer will be option [D].

Q12
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?
[A]. Displacement reaction
[B]. Precipitation reaction
[C]. Double displacement reaction
[D]. Precipitation reaction, and Double displacement reaction
Answer: Option D
Explanation:
This reaction is a double displacement reaction as well as a precipitation reaction. This is a double displacement reaction because one component of each compound has exchanged places with each other. It is also called a precipitation reaction due to the formation of white precipitate of barium sulphate. Rest other products formed are soluble in water except barium sulphate that precipitates out.

Q13
Solid Calcium Oxide Reacts Vigorously With Water To Form Calcium Hydroxide Accompanied By The Liberation Of Heat. This Process Is Called Slaking Of Lime Water. Which Among The Following Is/Are True About Slaking Of Lime Water And The Solution Formed?
[A]. It is an endothermic reaction, and It is exothermic reaction.
[B]. It is exothermic reaction, and The pH of the resulting solution will be more than seven.
[C]. It is an endothermic reaction, and The pH of the resulting solution will be less than seven.
[D]. The pH of the resulting solution will be more than seven, and The pH of the resulting solution will be less than seven.
Answer: Option B
Explanation:
Slaking of lime is an exothermic reaction because a large amount heat is produced during the reaction. The heat can be felt by touching the beaker from outside. The resulting compound Ca(OH)2, which is also called slaked lime, turns red litmus solution to blue and hence proves it to be a basic solution. Thus, the pH of this solution will be more than seven. You can easily understand by this equation: CaO + H2O → Ca(OH)2 + Heat

Q14
Consider The Given Statements And Choose The Incorrect One:
[A]. The bubbles of hydrogen gas are produced, when zinc granules reacts with dilute sulphuric acid.
[B]. Hydrogen gas is evolved when magnesium reacts with a dilute acid.
[C]. Hydrogen gas is evolved when dilute hydrochloric acid is poured over sodium carbonate.
[D]. None of the above.
Answer: Option C
Explanation:
Carbon dioxide gas is evolved when dilute hydrochloric acid is poured over sodium carbonate.

Q15
Which Among The Following Statement (S) Is (Are) True? Exposure Of Silver Chloride To Sunlight For A Long Duration Turns Grey Due To:
[A]. The formation of silver by decomposition of silver chloride.
[B]. The formation of silver by decomposition of silver chloride, and Decomposition of chlorine gas from silver chloride.
[C]. Sublimation of silver chloride, and Decomposition of chlorine gas from silver chloride.
[D]. Oxidation of silver chloride.
Answer: Option A
Explanation:
When silver chloride is exposed to sunlight, it is decomposed to form silver. During this reaction, white silver chloride changes into greyish white silver metal. This is also known as photolytic decomposition reaction as it takes place in the presence of sunlight. You can easily understand by this equation: 2AgCl + Sunlight → 2Ag(s) + Cl2

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