Matter and Its Composition Test - 8

Crystallisation is an easy process than distillation method and kills more microbes. Crystallization is a process separating a pure solid from a solution in its crystal form. 

Therefore, option a is correct.

Examples of non-flammable, non-toxic gases regularly used in workplaces include: compressed air, nitrogen, argon, carbon dioxide, and helium.

Therefore, option a is correct.

Melting is a process that causes a substance to change from a solid to a liquid. Melting occurs when the molecules of a solid speed up enough that the motion overcomes the attractions so that the molecules can move past each other as a liquid.

Therefore, option b is correct.

The volume of some substances decreases when melting; the volume of other substances increases when melting; and the volume of still other substances remains virtually constant when melting.

Therefore, option d is correct.

density is an Intensive property i.e it does not depend on mass or size. However, if you can increase the mass with keeping the volume constant at atomic level which is not possible then you can. That's because of the density difference. The density of iron is higher than density of paper.

Therefore, option a is correct.

Solidification, also known as freezing, is a phase change of matter that results in the production of a solid. Generally, this occurs when the temperature of a liquid is lowered below its freezing point. Solidification is nearly always an exothermic process, meaning heat is released when a liquid changes into a solid.

Therefore, option a is correct.

A distilling flask is a piece of laboratory equipment that is used to separate mixtures of two liquids with different boiling points.

Therefore, option a is correct.

In a liquid, particles will flow or glide over one another, but stay toward the bottom of the container. The attractive forces between particles are strong enough to hold a specific volume but not strong enough to keep the molecules sliding over each other.

Therefore, option b is correct.

Like a gas, plasma has no defined shape or volume. It can expand to fill a container. However, the particles in plasma are ionized (carry an electric charge) and very widely separated from each other. Examples of plasma include:

Lightning, Neon sign, Earth’s ionosphere, Stars etc.

Therefore, option d is correct.

Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.

Therefore, option c is correct.

Gases have three characteristic properties: 

(1) they are easy to compress.

(2) they expand to fill their containers.

(3) they occupy far more space than the liquids or solids from which they form. An internal combustion engine provides a good example of the ease with which gases can be compressed.

Therefore, option d is correct.

Condensation is the process where water vapor becomes liquid. Condensation happens one of two ways: Either the air is cooled to its dew point or it becomes so saturated with water vapor that it cannot hold any more water. Dew Point. Dew point is the temperature at which condensation happens.

Therefore, option b is correct.

Robert Brown, (born December 21, 1773, Montrose, Angus, Scotland—died June 10, 1858, London, England), Scottish botanist best known for his descriptions of cell nuclei and of the continuous motion of minute particles in solution, which came to be called Brownian motion.

Therefore, option a is correct.

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experimentation.

Therefore, option a is correct.

Filtration is a process by which insoluble solids can be removed from a liquid by using a filter paper. The liquid that passes through is called the filtrate and the undissolved solid particles are called residue. Example: A mixture of chalk powder and water can be separated by this method.

Therefore, option b is correct.