Class 10 : Practice Questions and Answers

Graphite is an excellent conductor of electricity because it has free electrons that move between layers of carbon atoms. This makes it useful in pencils and electrical applications.

Alcohols contain the hydroxyl group (-OH) as their functional group. This group makes alcohols soluble in water and gives them their characteristic properties.

Glucose is an organic compound because it contains carbon atoms bonded with hydrogen and oxygen, which are typical features of organic molecules.

Methane is a saturated hydrocarbon where all carbon atoms are connected by single bonds, making it less reactive than unsaturated hydrocarbons like ethene and ethyne.

The litmus test determines whether a substance is acidic or basic. Red litmus turns blue in a basic solution, and blue litmus turns red in an acidic solution.

Methane ($CH_4$) is a simple hydrocarbon consisting of one carbon atom bonded to four hydrogen atoms. It is the main component of natural gas.

Nitrogen is widely used in the production of fertilizers due to its essential role in plant growth. It is a key component of compounds like ammonium nitrate and urea.

Iron is a metal with properties like high conductivity and malleability. It is commonly used in construction and manufacturing.

When a fuel burns in oxygen, the products of combustion are typically water and carbon dioxide. This chemical reaction releases energy in the form of heat and light.

Hydrogen peroxide is represented by the formula $H_2O_2$. It consists of two hydrogen atoms and two oxygen atoms, and is commonly used as a disinfectant and bleaching agent.

Metals are ductile (can be drawn into wires) and malleable (can be hammered into thin sheets). These properties arise from the atomic arrangement that allows shape changes without breaking.

Calcium oxide is commonly known as quicklime. It is a white, caustic substance used in the production of cement and as a drying agent in various industrial processes.

Acids release hydrogen ions (H+) when dissolved in water. This gives them their characteristic properties, such as sour taste and the ability to turn litmus paper red.

Hydrochloric acid is a strong acid. It dissociates completely in water, releasing a high concentration of hydrogen ions, making it much stronger than weak acids like acetic or citric acid.

Sodium hydroxide is commonly known as caustic soda. It is a strong alkaline substance used in many industrial processes, such as soap making and water treatment.

When an acid reacts with a metal, it typically forms a salt and releases hydrogen gas. For example, hydrochloric acid reacts with zinc to form zinc chloride and hydrogen gas.

Burning a candle is a chemical reaction. The wax reacts with oxygen to produce carbon dioxide, water, and energy, changing the chemical composition of the substances involved.

Helium is a noble gas, which is chemically inert and doesn't readily form compounds with other elements due to its stable electron configuration.

A chemical reaction involves the transformation of one or more substances into new substances with different properties. It is a chemical change, not merely a physical one.

The spinal cord is part of the central nervous system that acts as a communication highway, transmitting nerve signals between the brain and the rest of the body while also coordinating reflex actions.