How many countries are there in the world?

Nrectangle pqrs, pq = 18, ps = 14, and pr = 22.8. diagonals pr¯¯¯¯¯ and qs¯¯¯¯¯ intersect at point t. what is the length of tq¯¯¯¯¯? a.7b.9c.11.4d.22.8

An earthquake’s epicenter can be determined from arrival time data recorded on a(

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks