แบบทดสอบรายวิชาวิทยาศาสตร์ 3 รหัสวิชา ว22101 เรื่องการแยกสาร

The most suitable method for separating sand mixed with salt is to dissolve the mixture in water and then filter it. This is because salt is soluble in water, while sand is not. By dissolving the mixture in water, the salt will dissolve, leaving the sand behind. The mixture can then be filtered to separate the sand from the solution.

The passage describes a method of separating solids from liquids by using a filter with appropriate-sized pores to trap solid particles, while allowing smaller liquid particles to pass through. The larger solid particles are therefore left on top of the filter. This process is called "การกรอง" in Thai, which means filtration.

Both options A and B are correct factors that affect the separation of substances from different parts of plants. The different types of solvents used can affect the solubility and separation of substances, while the size of the particles of the substance being extracted can also affect the efficiency of the separation process. Additionally, the odor of the substance can also play a role in the separation process.

The correct answer is "การสกัดด้วยตัวทำละลาย" (extraction with a solvent). This is because the question asks about a method of separating substances from different parts of a plant, specifically those with a pleasant smell and containing oil, such as turmeric. Extraction with a solvent involves using a solvent, such as ethanol, to dissolve the desired substances from the plant material, resulting in a concentrated solution or extract.

The answer states that the different types of solvents have different abilities to dissolve substances. Therefore, they are different from each other because each type of solvent has a different ability to dissolve substances.

The correct answer is "การกรองน้ำให้สะอาดเพื่อนำมาบริโภค" which means "Filtering water to make it clean for consumption". This answer suggests that students can use the method of separating substances in their daily lives by filtering water to remove impurities and make it safe to drink.

The given statement suggests that different types of substances dissolve better in different types of solvents. For example, yellow dye dissolves better in water than in ethanol, while essential oils from turmeric dissolve better in ethanol than in water. Therefore, to extract desired substances from plants, it is important to choose a suitable solvent. This explanation supports the answer choice "ถูกทุกข้อ" which means "all of the above".

The most suitable method for separating the sand and the nails is to pick the nails out. This method involves physically removing the nails from the sand, allowing for a complete separation of the two substances.

The correct answer is to use a filter funnel, magnet bar, and evaporate the remaining solution. This is because the mixture contains salt and water, which can be separated by using a filter funnel to separate the saltwater mixture. The mixture also contains iron powder, which can be separated using a magnet bar. Finally, the remaining solution can be evaporated to separate the dissolved substances from the water.

The suitable solvent for extracting oil from certain plants such as rice bran, soybean, palm, sesame, castor, and sunflower is hexane.