Chemistry in Class 10 : Practice MCQ Questions & Answers with Explanations

A decomposition reaction occurs when a compound breaks down into two or more simpler substances, represented as $AB \rightarrow A + B$.

Ethene is an unsaturated hydrocarbon because it contains a double bond between two carbon atoms, giving it fewer hydrogen atoms than saturated hydrocarbons.

Mercury is the only metal that remains liquid at room temperature. This unique property makes it useful in thermometers and other instruments.

Acetic acid is the main acid found in vinegar. It gives vinegar its characteristic sour taste and is widely used in cooking and as a preservative.

Ethanol is a versatile compound used as a fuel, a solvent in cleaning products, and as a food preservative.

Carbon dioxide is essential for photosynthesis. Plants use it along with water and sunlight to produce glucose and oxygen.

When zinc reacts with hydrochloric acid, hydrogen gas is released along with zinc chloride. This is a typical reaction of metals with acids.

In a double bond, one bond is a sigma bond and the other is a pi bond. The pi bond is formed by the sideways overlap of p-orbitals between the two carbon atoms.

Oxygen is essential for respiration. Cells use oxygen to break down glucose, releasing energy needed to function.

When an acid is added to water, it dissociates to release hydrogen ions (H+), making the solution acidic with a pH below 7.

Alkynes contain at least one triple bond between carbon atoms, making them unsaturated hydrocarbons with fewer hydrogen atoms than alkanes.

Lemon juice is acidic with a pH of approximately 3. Acids have a pH below 7, and lemon juice is naturally acidic due to the presence of citric acid.

In a displacement reaction, one element displaces another from a compound. In $A + BC \rightarrow AC + B$, element A displaces B from BC to form AC.

The IUPAC name for $CH_3\text{-}CH_2\text{-}CH=CH_2$ is 1-butene, as the double bond is between the first and second carbon atoms from the end closest to the double bond.

Non-metals typically form acidic oxides, not basic ones. For example, carbon dioxide is an acidic oxide, whereas metals like sodium form basic oxides.

Zinc is commonly used to coat metals like iron through galvanization, forming a protective layer that shields iron from rust and corrosion.

In $Cl_2$, chlorine has an oxidation state of 0. In $FeCl_3$, chlorine has an oxidation state of $-1$, while iron has $+3$. This highlights oxidation and reduction in the reaction.

Nylon is a synthetic polymer formed from carbon-based monomers. It is used in fabrics and various industrial applications due to its strength and flexibility.

In $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$, zinc is oxidized (loses electrons) and copper is reduced (gains electrons). This simultaneous oxidation and reduction makes it a redox reaction.

According to the Bronsted-Lowry theory, a base accepts a proton (H+) while an acid donates a proton. This expands the definition of acids and bases beyond the traditional Arrhenius concept.