Matter & Mixtures — Set 1
Chemistry · पदार्थ और मिश्रण · Questions 1–10 of 50
Which of the following is considered a pure substance in chemistry?
Correct Answer: A. Distilled water
Distilled water consists only of water molecules and has a fixed composition. Pure substances cannot be separated into other kinds of matter by any physical process. It is distinct from mixtures like air or milk which contain multiple components.
What type of mixture is a solution of sugar in water?
Correct Answer: A. Homogeneous
A sugar solution is a homogeneous mixture because its composition is uniform throughout. The particles are distributed at the molecular level and do not settle over time. Such mixtures are also simply called true solutions.
Which state of matter has a definite shape and a definite volume?
Correct Answer: C. Solid
Solids have a definite shape and volume due to the strong intermolecular forces between particles. The particles are closely packed and can only vibrate about their fixed positions. This rigidity makes them incompressible under normal conditions.
The process of a solid changing directly into a gas is called?
Correct Answer: B. Sublimation
Sublimation occurs when a substance transitions from a solid state to a gaseous state without passing through the liquid phase. Common examples include dry ice and naphthalene balls. This process happens when the vapor pressure of the solid exceeds the atmospheric pressure.
Which of the following is a characteristic of a compound?
Correct Answer: A. Chemical bond formation
A compound is formed when two or more elements combine chemically in a fixed ratio. The properties of a compound are entirely different from its constituent elements. Energy is usually absorbed or evolved during the formation of a compound.
What is the common name for a mixture of two or more metals?
Correct Answer: D. Alloy
An alloy is a homogeneous mixture of two or more metals or a metal and a non-metal. Alloys are created to enhance the properties of metals, such as increasing strength or resistance to corrosion. Steel and bronze are well-known examples of alloys.
In a colloidal solution, the phase that is spread throughout is known as the?
Correct Answer: C. Dispersed phase
The dispersed phase represents the particles that are distributed in a continuous medium. In milk, for example, fat globules act as the dispersed phase. The size of these particles typically ranges from 1 to 1000 nanometers.
Which method is best suited to separate a mixture of sand and salt?
Correct Answer: D. Filtration after dissolving in water
Salt dissolves in water while sand remains insoluble, allowing for separation by filtration. Once the sand is filtered out, salt can be recovered from the water by evaporation. This process relies on the difference in solubility between the two substances.
Which of the following is a chemical change?
Correct Answer: D. Rusting of iron
Rusting of iron is a chemical change because it results in the formation of a new substance, iron oxide. This process is irreversible and involves a chemical reaction with oxygen and moisture. Most chemical changes are accompanied by energy changes.
The movement of particles from a region of higher concentration to lower concentration is?
Correct Answer: A. Diffusion
Diffusion is the spontaneous mixing of particles until a uniform concentration is achieved. It occurs most rapidly in gases due to the high kinetic energy of the particles. An example is the smell of perfume spreading in a room.