According to Wegener's theory, why were tropical plant fossils found in Arctic islands? Plants were more adaptable in the past.
O The poles of Earth were warmer in the past.
O Arctic islands were closer to the equator in the past.
O Land movements warmed the landmasses in the past.

Read the given expression. x = number of protons − number of core electrons which of the following explains the identity of x and its trends across a period? x is the effective nuclear charge, and it remains constant across a period. x is the screening constant, and it remains constant across a period. x is the effective nuclear charge, and it increases across a period. x is the screening constant, and it increases across a period.

An aqueous solution of potassium hydroxide is standardized by titration with a 0.194 m solution of hydrobromic acid. if 25.2 ml of base are required to neutralize 24.2 ml of the acid, what is the molarity of the potassium hydroxide solution? m potassium hydroxide

Calculate the percent composition by mass of each element in al(oh)3. use at least three significant figures.