Is know an abstract noun

What is a set of genes that determine a trait? Which food goes from mouth to stomach? Which is an example of a physical change A Gasoline ignites B Water evaporates C Wood rots D A nail rusts? Which African city is located at 45 degrees east longitude and just above the equator? Give two reason for the elasticity in cartilage? Why can the living things survive in the pond? How does oxide help protect from uv rays? What best describes the mass of protons neutrons and electrons? The prone position is a position in which the body is lying face down? Are taste buds real? At an old gas station gasoline leaks from an underground storage link is this Toxic sediment nutrient or bacterial pollution? What is the best way to describe human nature? Can we see nerve cell with our naked eyes? A graph shows how the temperature of a substance changes as energy is added steadily over time. Which part of the graph would indicate a phase change is taking place? Behind which type of front might lower temperatures be expected? Is the density of 1 liter of olive oil the same as the density of 4 liters of olive oil? What is the purpose of the emulsifier in ice cream? What is the type of bonding in magnesium salt X? Is polenta starch? Why does ice have a high melting point compared to the solid state of other liquids?