Class 10 Science Chapter 1 MCQ

A combination reaction is one in which or more reactants combine to form a single product. MgO and H2O combine to from Mg (OH)2. 4Al and 3O2 combine to form Al2O3. A combination reaction is also known as synthesis reaction. Hence, your answer will be option [D].

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.

Here are all the statements are correct. Hence, your answer will be option [D].

LPG on combustion produced carbon dioxide, water and heat is produced. This reaction is irreversible. Thus combustion of LPG is not physical change.

Oxygen displaces H from NH3 and oxygen oxides NH3 to NO it gets reduced.

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.

Here are all the statements are correct. Hence, your answer will be option [D].

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 gas.

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.

The chemical reaction between barium hydroxide and ammonium chloride to form barium chloride, ammonia and water is characterized by a change in temperature. (Here, is a fall in temperature.)

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.

A precipitate is a “Solid product” which separate out from the solution during a chemical reaction.

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

Carbon dioxide gas is evolved when dilute hydrochloric acid is poured over sodium carbonate.

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

Here are all the statements are correct. Hence, your answer will be option [D].

Double displacement reactions are such chemical reactions in which one component of each reactant exchange to form products. The cations and anions of two compounds exchange their ions to form two new compounds. Here only in reaction (B), ions of both reactants are exchanged and two entirely different compounds are formed.

Magnesium ribbon which we use usually has a coating of magnesium oxide on its surface which is formed by the slow action of oxygen of air on it. So, before burning in air, the magnesium ribbon is cleaned with sandpaper. This is done to remove the protective layer of magnesium oxide from the surface of magnesium ribbon. So, that it may readily combined with the oxygen of air on heating.

Chemical reaction in beakers A and B gives out heat. Hence, the temperature of the solution increases. We can call it an exothermic reaction. In beaker C, heat is absorbed from water instead and hence the temperature decreases. Now, we can call it an endothermic process.

The burning of magnesium in air to form magnesium oxide. It is an example of a chemical reaction. In this chemical reaction, there are two reactants magnesium and oxygen but there is only one product magnesium oxide. The properties of the product magnesium oxide are entirely different from those of the reactants magnesium and oxygen.

When quick lime reacts with water, calcium hydroxide is produced and a large amount of heat is released. Similarly, when an acid or a base is diluted with water, heat is released making it a highly exothermic reaction.

Here are all the statements are correct. Hence, your answer will be option [D].

Iron is getting oxidized and forming ferrous ferric oxide (Fe3O4)4. Water molecule is getting reduced to hydrogen ions. Water is acting as an oxidizing agent by donating its oxygen atom to Fe.

This is a redox reaction because oxidation and reduction both are happening simultaneously. It is also a displacement reaction because H of NH3 is displaced by oxygen. A displacement reaction is also a redox reaction as it is always followed by oxidation as well as reduction. Note: When oxygen is added to a compound in a reaction, it is called oxidation. Removal of oxygen from a substance during a reaction is called reduction.

Combustion of Liquefied Petroleum Gas (LPG) is not a physical change. It is a chemical change because combustion of LPG produces new substances. A lot of heat is produced along with carbon dioxide and water vapour during this reaction. It is also irreversible in nature. Rest three are physical changes as no new products are formed; the only state of the substance changes. Hence, your answer will be option [D].