The average atomic mass if the element above is calculated by the sum of the product of the isotope abundance and its atomic mass unit. It is expressed as:
Average atomic mass = Σ xi(Mi)
<span>Average atomic mass = (.7547 x 248.7) + (.2453 x 249.4) = 248.87
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Hope this helps.
They diffuse through small pores at the bottom of the leaf called stomata.
Plants can open and close their stomata, they open them to get water and carbon dioxide in but then close them to ensure the water doesn't 'leak' back out. This is important for plants growing in drier conditions like the cactus.
Yes. They are called compound machines because two or more simple machines were combined to create it.