The question asks to identify the scientist who proposed the principle stating that equal volumes of all gases, under identical conditions of temperature and pressure, contain an equal number of molecules. This is a fundamental concept in chemistry related to the behavior of gases.
Based on this, Avogadro's statement precisely matches the principle described.
B) Avogadro — Avogadro's Law states that equal volumes of all gases, under similar conditions of temperature and pressure, contain equal numbers of molecules.
The question asks about the concerns associated with Brominated Flame Retardants (BFRs) used in household products. We need to evaluate two statements regarding their environmental persistence and bioaccumulation.
Brominated Flame Retardants (BFRs) are a group of organobromine compounds that are added to a wide range of products to reduce their flammability. A significant concern with many BFRs is their chemical stability, which makes them persistent organic pollutants (POPs). This means they do not break down easily in the environment through natural processes like microbial degradation, photolysis, or hydrolysis. Their persistence allows them to remain in the environment for long periods, leading to widespread contamination.
Therefore, Statement 1 is correct.
Due to their lipophilic (fat-loving) nature and persistence, BFRs can bioaccumulate and biomagnify in the food chain. This means they are absorbed and stored in the fatty tissues of organisms and their concentrations increase at higher trophic levels. Humans and animals can be exposed to BFRs through diet, dust inhalation, and dermal contact. Once absorbed, they can remain in the body for extended periods, leading to potential health effects.
Therefore, Statement 2 is correct.
Since both statements are correct, the option that includes both 1 and 2 is the right answer.
C) Both 1 and 2 — Both statements accurately describe the environmental and health concerns associated with Brominated Flame Retardants. They are persistent in the environment and can accumulate in living organisms, posing risks.
This question asks about the relationship between the rate of diffusion of a gas and its properties like density or molecular mass. This concept is governed by Graham's Law of Diffusion.
Correct Option: D) Inversely proportional to the square root of its molecular mass
Graham's Law of Diffusion states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular mass (or molar mass) at constant temperature and pressure. This is the most direct and fundamental statement of the law.
The question asks which phenomena increase with rising temperature. We need to analyze the effect of temperature on each phenomenon listed in the options: diffusion, evaporation, compression of gases, solubility, and expansion of gases.
C) Evaporation, diffusion, expansion of gases — As explained above, all three phenomena (evaporation, diffusion, and expansion of gases) increase when the temperature is raised due to the increased kinetic energy of particles.
The question asks under which conditions the distance between hydrogen gas molecules would increase. This relates to the concept of gas density and volume. An increase in the average distance between molecules implies a decrease in the density of the gas or an increase in the volume occupied by the same amount of gas.
According to Boyle's Law, for a fixed amount of gas at constant temperature, pressure is inversely proportional to volume (\(P \propto 1/V\)). If pressure increases, the volume occupied by the gas decreases. A decrease in volume means the molecules are forced closer together, thus the distance between them would decrease, not increase.
If some hydrogen gas leaks out, the number of gas molecules inside the container decreases. Assuming the volume of the container remains constant, fewer molecules will occupy the same space. This leads to a decrease in the concentration of molecules, and consequently, the average distance between the remaining molecules will increase.
If the volume of the container increases while the amount of gas remains constant, the same number of molecules now have more space to move around. This directly leads to an increase in the average distance between the molecules.
Adding more gas means increasing the number of molecules within the same fixed volume. This increases the concentration of molecules, causing them to be closer to each other. Therefore, the average distance between molecules would decrease, not increase.
Based on the analysis, conditions (ii) and (iii) are the ones that lead to an increase in the distance between hydrogen gas molecules.
Correct Option: D) (ii) and (iii) only
The question asks to identify the phenomenon responsible for the cooling of water in an earthen pot during summer. This is a common observation based on principles of heat transfer and phase change.
Correct Option: D) Evaporation — As explained above, the porous nature of the earthen pot allows water to seep to the surface, where it evaporates. Evaporation is a cooling process because it absorbs latent heat from the remaining water, thereby cooling it.