If the half life for strontium-90 is approximately 28 years, then what is the whole life for strontium-90? there is no answer choices plz

The figure is a square. its diagonals meet to form four right angles. what is the approximate value of x? 2.8 units 3.3 units 4.0 units 5.7 units

Which of the following would not be considered a geographic impact on the history of middle and south america? a. the relative geographic isolation of the americas meant that they would be more susceptible to european diseases. b. ernesto “che” guevara's trip throughout south america inspired him to become a revolutionary. c. the tropical climate of north america has encouraged many south american countries to produce goods there. d. the proximity of the united states to middle and south america has strengthened its relationship to the region.

Scientists learn about the temperature and pressure near the earth’s core by studying rock. a) compacted b) igneous c) metamorphic d) sedimentary