How many electrons must be removed from each of two 5.400 kg copper spheres to make the electric force of repulsion between them equal in magnitude to the gravitational attraction between them? Give your answer in scientific notation.

This line graph compares the growth of plants that were kept in the sun for different amounts of time.a)  on day 7, the plants kept in the sun for 3 hours were how tall? b)  on day 7, the plants kept in the sun for 6 hours were how tall? c)    on day 10, the plants kept in the sun for 9 hours were how tall? d)  on day 11, the plant that was grown with 1 hour of sunlight was how tall? e)  based on the graph, the plant grows best in what amount of sunlight?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

If 1.8 l of water is added to 2.5l of a 7.0 m koh solution, what is the molarity of the new solution