Explanation

A dental filling is an example of a solution where a liquid (like mercury) is dissolved in a solid (like silver or tin).

This mixture forms a solid solution used to restore damaged teeth.

Explanation

Silver reacts with hydrogen sulphide (H₂S) in the air to form black silver sulphide (Ag₂S) coating.

This process is called tarnishing.

Explanation

Sodium hydroxide is commonly known as caustic soda.

It is a strong base used in soap making and other chemical industries.

Explanation

Potassium permanganate (KMnO₄) gives a pink to purple color when dissolved in water, depending on the concentration.

It is commonly used as a disinfectant and in redox reactions.

Explanation

In the lab, oxygen gas is prepared by heating potassium chlorate (KClO₃) in the presence of manganese dioxide (MnO₂) as a catalyst.

MnO₂ speeds up the decomposition of KClO₃ without being consumed.

Explanation

Sand is primarily composed of silicon dioxide (SiO₂), formed when silicon and oxygen combine.

It is a common natural material found in deserts, beaches, and riverbeds.

Explanation

Explanation

Calcium chloride (CaCl₂) is a hygroscopic substance, meaning it absorbs moisture from the air.

It is commonly used as a drying agent in desiccators to keep the environment moisture-free.

Explanation

Casein plastic is made by adding an acid (like vinegar) to milk, which causes the casein protein to form a solid.

This solid can be molded and dried to create a type of early plastic, known as casein plastic.

Explanation

Dry ice sublimation is a physical change where solid CO₂ directly turns into gas without changing its chemical composition.

Rusting of iron, burning of wood, and cooking of egg are all chemical changes, where new substances are formed.