The balanced chemical equation when sodium is exposed to air is ____.

Correct! Wrong!

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In a balanced chemical equation the number of atoms of different elements should be equal on the reactant side and the product side. Number of sodium atoms on both sides is 4. Number of oxygen atoms on both sides is 2. Hence, the equation is balanced.

The process of decomposition of silver bromide to silver and bromine is used in ____.

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The process of decomposition of silver bromide to silver and bromine is used in black and white photography.

One observation that helps us to say a chemical reaction has taken place is change of temperature.

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Heat may be evolved or absorbed during a reaction. So, a chemical reaction can be identified by the change of temperature.

Which of the following reactions will not take place?

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There is no reaction between silver and copper nitrate, since, silver is less reactive than copper.

The symbol △ in a chemical equation indicates ____.

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The symbol △ in a chemical equation indicates heat.

Explosion of crackers is an example of a ____ reaction.

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Explosion of crackers is a combustion reaction, since, it produces heat, light and sound energy.

Iron can be prevented from corrosion by alloying iron with ____.

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Iron can be prevented from corrosion by alloying with nickel and chromium.

The reaction of lime with water to form calcium hydroxide is an ____ reaction.

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The reaction of lime with water to form calcium hydroxide is an exothermic combination reaction. When lime is added to water, calcium hydroxide is formed along with the liberation of a large amount of heat.

Identify the balanced chemical equation for the reaction Hydrogen + Chlorine → Hydrogen chloride.

Correct! Wrong!

The balanced chemical equation for the reaction Hydrogen + Chlorine → Hydrogen chloride is: H2 +Cl2 →2HCl In a chemical reaction the number of atoms of different elements should be equal on the reactant side as well as the product side. Number of hydrogen atoms on both sides is 2. Number of chlorine atoms on both sides is 2. Hence, the equation is balanced.

The colour of the substance formed when silver chloride is exposed to sunlight is ____.

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When white coloured silver chloride is exposed to sunlight it changes to gray due to the formation of silver.

On heating copper powder in a china dish, it turns black due to the ____.

Correct! Wrong!

The black substance formed when copper is heated is copper (II) oxide formed due to the oxidation of copper.

Which of the following is not a decomposition reaction?

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In the process of photosynthesis carbon dioxide and water combine to form starch, hence, it is a combination reaction.

The symbol (↓) mentioned next to a substance in a chemical equation indicates ____.

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The symbol (↓) in a reaction indicates that a precipitate is formed.

When iron nails are dropped in a copper sulphate solution, then ____.

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When iron nails are dropped in copper sulphate the blue colour changes to green. Iron, being more reactive than copper displaces copper from the copper sulphate solution.

Decaying of vegetable matter is a ____ reaction.

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Decaying of vegetable matter is a exothermic decomposition reaction. In the decaying process, the vegetable matter is broken down to simple substances, liberating heat.

Quick lime is ____.

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CaO is the formula of quick lime.

The chemical reaction in which heat is evolved is called ____ reaction.

Correct! Wrong!

A chemical reaction in which heat is evolved is called an exothermic reaction.

Which amongst the following represents a photochemical decomposition?

Correct! Wrong!

Silver bromide decomposes when exposed to light to form metallic silver and bromine gas; hence, it is a photochemical decomposition.

Fatty foods become rancid due to the process of ____.

Correct! Wrong!

Rancidity is the natural oxidation of fatty foods.

The subscript (s) mentioned after a symbol or formula of a substance, in a chemical equation indicates ____.

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The subscript (s) mentioned after a symbol or formula of a substance, in a chemical equation indicates that the physical state of that substance is solid.

In the reaction Zn + 2AgNO3 → Zn (NO3) 2 + 2Ag, the substance oxidized is ____.

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In the reaction Zn + 2AgNO3 → Zn(NO3)2 + 2Ag, O is added to Zn, hence, Zn is oxidized. In the reaction Zn + 2AgNO3 → Zn(NO3)2 + 2Ag, O is added to Zn, hence, Zn is oxidized.

In a precipitation reaction, one of the products formed is ____.

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In a precipitation reaction, aqueous solution of two salts react and one of the products formed is a precipitate, which is an insoluble salt.

During the electrolytic decomposition of water, hydrogen gas is collected at the ____.

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During the electrolytic decomposition of water, H+ ion and O−2 ion are formed. H+ ion being positive gets deposited at the cathode.

The pungent smelling gases formed when ferrous sulphate crystals are heated strongly are ____.

Correct! Wrong!

When ferrous sulphate crystals are heated strongly, they decompose to form iron (III) oxide and pungent smelling gases, sulphur dioxide and sulphur trioxide.

The products formed when CuCO3 is heated are ____.

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The products formed when CuCO3 is heated are CuO and CO2. The reaction is: CuCO3 → CuO + CO2

Which of the following is the first step to write an equation?

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Equations contain both symbols and formulae. Therefore, to write an equation, first the statement should be changed to symbols and formulae.

To prevent iron from rusting, iron sheets are dipped in a molten zinc solution. This process is known as ____.

Correct! Wrong!

The process of depositing a thin layer of zinc on iron is called galvanisation.

A metal M forms a chloride of the type MCl2.The valency of the metal with respect to chlorine is ____.

Correct! Wrong!

The valency of metal with respect to chlorine is 2.

The colour of ferrous sulphate solution when copper turnings are dropped in it ____.

Correct! Wrong!

There is no change in colour when copper turnings are dropped in ferrous sulphate solution, since, reaction does not take place. Copper is less reactive than iron and hence, does not diplace iron.

A chemical equation is represented by using only formulae.

Correct! Wrong!

A chemical equation is represented by using both symbols and formulae.

CBSE Class 10th Science 1 - CHEMICAL REACTIONS AND EQUATIONS MCQs
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