Which objective lens requires oil to be applied?
Multiple choice.

Choice A rationale: Hypotonic is incorrect because hypotonic is a type of solution that has a higher concentration of water and lower concentration of solute than the cell placed in the solution. In a hypotonic solution, water moves into the cell and out of the solution by osmosis, causing the cell to swell.

Choice B rationale: Isotonic is correct because isotonic is a type of solution that has the same concentration of water and solute as the cell placed in the solution. In an isotonic solution, there is no net movement of water across the cell membrane.

Choice C rationale: Diffusive is incorrect because diffusive is an adjective that describes the movement of molecules from a region of high concentration to a region of low concentration, not a type of solution. Diffusion is the process by which molecules move across a membrane or a space due to their random motion.

Choice D rationale: Osmotic is incorrect because osmotic is an adjective that describes the movement of water across a semipermeable membrane, not a type of solution. Osmosis is the process by which water moves from a region of high water concentration to a region of low water concentration.

Choice E rationale: Hypertonic is incorrect because hypertonic is a type of solution that has a lower concentration of water and higher concentration of solute than the cell placed in the solution. In a hypertonic solution, water moves out of the cell and into the solution by osmosis, causing the cell to shrink.

Choice A rationale: Movable is correct because motile is an adjective that describes the ability of an organism or a cell to move by itself, using some form of locomotion, such as flagella, cilia, or pseudopodia. For example, some bacteria, protists, and sperm cells are motile.

Choice B rationale: Fixed is incorrect because fixed is the opposite of motile. Fixed is an adjective that describes the inability of an organism or a cell to move by itself, due to being attached to a substrate or a surface. For example, some plants, fungi, and coral are fixed.

Choice C rationale: Magnification is incorrect because magnification is not related to motility. Magnification is a measure of how much larger an image appears compared to the actual size of the object. Magnification is used in microscopy to observe small objects, such as cells.

Choice D rationale: Solid is incorrect because solid is not related to motility. Solid is a state of matter that has a definite shape and volume, due to the strong attraction between the molecules. Solid is contrasted with liquid and gas, which have no definite shape and can flow.