[填空题]
Calculate (a) the rm b4b28, yyuzk vmcgui9-o4,c wz k27mr-h0 ) yznx50oeq/a hrrs speed of an oxygen molecule at 0 $^{\circ} $ C m/s
(b) determine how many times per second it would move back and forth across a 7.0-m-long room on the average, assuming it made very few collisions with other molecules. round trips per sec