Answer:
For example, to make 70% ethanol from 95% ethanol, take 70 mL of 95% ethanol and add enough water to bring the volume to 95 mL. You will then have 95 mL of 70% ethanol. This works for any dilution and all that is required is a large enough graduated cylinder.
When using liquid reagents, the percent concentration is based upon volume per volume, i.e. #ml/100ml. Example 2: If one wished to make a 70% ethanol solution, 70 ml of 100% ethanol would be dissolved in 30 ml of water (or the equivalent for whatever volume was needed).
Primary production within the open ocean is mainly through diatoms which are single-celled photosynthesising organisms. Although the concentration of productivity in the open ocean is relatively low, the vast area of the ocean means that this form of productivity contributes greatly to overall primary production on Earth. There are also regions of relatively high production from diatoms in certain parts of the ocean. This is because the productivity of diatoms is limited by a lack of certain essential nutrients in the ocean, such as iron and silica, which tend to sink to greater depths in the ocean than the surface layers that the diatoms inhabit. In these regions, upwelling occurs, bringing nutrients from the deep ocean to the surface, and resulting in diatom blooms. This occurs typically on the west coasts of continents, because upwelling occurs here due to something called the Bernoulli Effect, which relates the the way the Earth spins. This is why very productive fishery areas are usually found on the west coasts of continents, at least in the Southern Hemisphere, and why the seawater is cold in these regions.
Answer:
d the amount of matter in a closed system is the same at the start of a reaction as at the end of the reaction
The last choice is the correct answer