What major natural barrier did it cross?

Social mobility: social mobility refers to our chances of moving up or down within the american class structure. what do you think is the most important factor that leads to upward mobility? and why do you feel that way? race or ethnicity gender social class at birth hard work and education

An object weighs 40n in air , weighs 20n when submerged jn water and 30n submerged in a liquid of unknown density .what is the density of the liquid?

Though most presidents have claimed affiliation with a christian church, the only roman catholic president has been a) abraham lincoln. b) john f. kennedy. c) george washington. d) franklin d. roosevelt.