Matter In Our Surroundings

Dry ice refers to solid carbon dioxide (CO2) which is commonly used as a cooling agent. It is called "dry" ice because it does not melt into a liquid like regular ice, but instead sublimates directly from a solid to a gas. Therefore, the correct answer is "Solid" as it accurately describes the physical state of dry ice.

During summer, water kept in an earthen pot becomes cool because of evaporation. As the temperature rises, the water molecules gain energy and start to move faster. Some of these molecules at the surface gain enough energy to break free from the liquid and enter the air as vapor. This process is called evaporation. As the water evaporates from the surface of the earthen pot, it takes away heat energy, resulting in a cooling effect. The porous nature of the earthen pot allows for more evaporation, enhancing the cooling effect.

Gas is the state of matter that has minimum interparticle attraction. In a gas, the particles are widely spaced and have high kinetic energy, which leads to weak forces of attraction between them. This allows the particles to move freely and independently, resulting in a fluid and easily compressible state. In contrast, solids have strong interparticle attractions, which keep the particles closely packed in a fixed arrangement. Liquids have moderate interparticle attractions, allowing them to flow and take the shape of their container but not as freely as gases. Therefore, the correct answer is gas.

In order to liquefy a gas, both temperature and pressure need to be manipulated. Low temperature helps to reduce the kinetic energy of the gas particles, causing them to move slower and come closer together. High pressure further compresses the gas, reducing the space between the particles and increasing the intermolecular forces. Therefore, the correct set of conditions for liquefying gas is low temperature and high pressure.

The melting point of a substance is defined as the constant temperature at which both the solid and liquid phases of the substance coexist in equilibrium. This means that at the melting point, the substance is transitioning from a solid to a liquid, but both phases are present simultaneously. This is why the correct answer is "Both the solid & liquid exist together."

Increasing the temperature would increase the rate of evaporation, as higher temperatures provide more energy for the molecules to escape from the liquid phase. Diffusion is also affected by temperature, as higher temperatures increase the kinetic energy of the molecules, leading to faster movement and therefore faster diffusion. Expansion of gases is directly related to temperature, as gases expand when heated due to the increased kinetic energy of the molecules. Therefore, all three phenomena - evaporation, diffusion, and expansion of gases - would increase on raising the temperature.

During boiling, cooling is not caused but rather heating occurs. When a substance boils, it absorbs heat from its surroundings and converts into vapor. This process requires energy, which results in a rise in temperature rather than cooling. Therefore, the statement "Cooling is caused during boiling" is incorrect.

The correct order of substances in increasing order of attraction between the particles is oxygen, water, and sugar. This means that oxygen has the weakest attraction between its particles, followed by water, and then sugar.

The correct statement is "Conversion of solid into vapors without passing through the liquid state is called sublimation." Sublimation is the process by which a solid directly changes into a gas without going through the liquid phase. This occurs when the vapor pressure of the solid is higher than its melting point. An example of sublimation is when dry ice (solid carbon dioxide) changes directly into carbon dioxide gas without melting into a liquid state.

When solid CO2 (also known as dry ice) changes into vapors, it undergoes a process called sublimation. This occurs when the temperature increases and the pressure decreases. The increase in temperature provides the energy needed to break the intermolecular forces holding the solid together, allowing it to transition directly into a gas. At the same time, the decrease in pressure reduces the forces pushing the molecules closer together, facilitating the conversion into vapor. Therefore, both a decrease in pressure and an increase in temperature are responsible for the change of state from solid CO2 to vapors.

Sodium bromide has the strongest interparticle forces among the given options. This is because sodium bromide is an ionic compound, consisting of positively charged sodium ions and negatively charged bromide ions. Ionic compounds have strong electrostatic attractions between the oppositely charged ions, resulting in strong interparticle forces. On the other hand, ammonia, carbon dioxide, and ethyl alcohol are molecular compounds that have weaker interparticle forces such as hydrogen bonding, dipole-dipole interactions, or London dispersion forces.

The evaporation of a liquid can occur at all temperatures. Evaporation is a process in which molecules at the surface of a liquid gain enough energy to escape into the gas phase. This process can happen at any temperature, although the rate of evaporation may vary depending on the temperature. Even at low temperatures, some molecules will still have enough energy to escape from the liquid's surface and undergo evaporation. Similarly, at higher temperatures, more molecules will have enough energy to evaporate. Therefore, evaporation can occur at all temperatures.

On the Kelvin scale, 0 degrees Celsius is equal to 273 Kelvin. The Kelvin scale starts at absolute zero, which is the point at which all molecular motion ceases. In the Celsius scale, 0 degrees represents the freezing point of water, but on the Kelvin scale, this is equivalent to 273 Kelvin. Therefore, 0 degrees Celsius is equal to 273 Kelvin.

The melting point of a substance is the temperature at which both the solid and liquid phases of the substance coexist in equilibrium. At this temperature, the solid is partially melted and transformed into a liquid, but there is still some solid present. It is a crucial point as it indicates the temperature at which a substance transitions from a solid to a liquid state.

When we add sugar in water, the particles of sugar are very small and can easily dissolve in the water. They also get into the spaces between water particles due to their small size. Additionally, the particles of sugar are constantly moving due to the random motion of particles in a liquid. Therefore, all of these factors contribute to the disappearance of sugar particles when added to water.