Cuestionario de Química

Which of the following modifications in the movement of particles explains the transition from solid to liquid when the temperature increases, according to Kinetic Molecular Theory?

• An increase in the mass of the particles

• A decrease in the kinetic energy of the particles

• A decrease in the internal energy of the particles

• A reduction in the speed of the particles

• An increase in the kinetic energy of the particles

If we have a homogeneous mixture of two liquids with very different boiling points, what distillation method is most suitable for separating both components?

• Extractive distillation.

• Fractional distillation.

• Simple distillation.

• Vacuum distillation.

• Azeotropic distillation.

If ice is heated and turns into water, what state change occurs?

• Solidification

• Evaporation

• Melting

• Sublimation

• Condensation

Which of the following correctly distinguishes a pure substance from a mixture?

• A pure substance is characterized by the possibility of separating its components by mechanical means, while in a mixture the elements are permanently bonded.

• In a pure substance, the components are physically combined, while in a mixture they are chemically bonded to form a new substance.

• A pure substance can be separated into its components by physical methods, unlike a mixture, which requires chemical separation.

• A pure substance has a fixed composition and defined properties (as in the case of elements or compounds), while in a mixture the components are physically combined and retain their individual characteristics.

• Mixtures have a constant composition and unique properties, unlike pure substances, which exhibit variations in composition.

Which of the following correctly differentiates a pure substance from a mixture, considering that the former always has defined properties and the latter can present variations in its physical properties?

• A pure substance has a constant composition, but its melting point varies with the amount of sample.

• A mixture shows invariable physical properties, regardless of its components.

• A pure substance has a constant composition and a defined melting point.

• A pure substance is composed of several components in variable proportions.

• A mixture has a constant composition and a defined melting point.

Considering that ethanol and hexane are substances that change from liquid to gas when energy is applied; which of the following options best explains why ethanol boils at a higher temperature than hexane?

• Ethanol has a higher vapor pressure, which is incorrectly related to the need for more energy to vaporize it.

• Ethanol has more rigid covalent bonds, which are incorrectly associated with a greater energy required to break them and change state.

• Hexane has a greater molecular mass, which supposedly increases its intermolecular forces and raises its boiling point.

• Hexane forms stronger dipole-dipole interactions, which would facilitate its change of state at a lower temperature.

• Ethanol forms hydrogen bonds that intensify its intermolecular forces, requiring more energy for its vaporization.

Considering that physical properties allow us to identify measurable characteristics of a substance without changing its composition; which of the following options is an example of a physical property?

• Calorific value

• Acid-base behavior

• Oxidizing power

• Boiling point

• Reactivity with oxygen

In a laboratory, two samples are being examined: distilled water and saline solution. Which of the following statements correctly describes the difference between the two samples?

• Distilled water is a pure substance, and the saline solution is a heterogeneous mixture, as its components can be distinguished.

• Both samples are pure substances, as they have a fixed composition despite the dissolution of the salt.

• Distilled water is a pure substance, and the saline solution is a homogeneous mixture.

• Distilled water is a homogeneous mixture, and the saline solution is a pure substance.

• Distilled water and the saline solution are mixtures, as they show variations in the composition of their components.

During the melting of ice, energy is absorbed to break the intermolecular forces and transform it into water. How is this change of state classified energetically?

• Endothermic

• Exothermic

• Adiabatic

• Catalytic

• Isothermal

In an experiment, there is a heterogeneous mixture of sand and water; what separation method allows for the recovery of sand without altering its properties?

• Centrifugation

• Distillation

• Evaporation

• Decantation

• Filtration