Calculate the number of atoms in each of the following samples: 19. 0.357 mole sample of potassium 20. 2.93 moles sample of ca 21. 473 moles of copper 22. an 85.5-g sample of hg in a barometer 23. a 0.251-g ti metal heart valve 24. a 1.00-g sample of kr gas

Draw the lewis dot structure for each of the following polyatomic ions

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of

When did stem cell research become known ? who discovered stem cell? what experiments or studies have been conducted so far?