Use the periodic table to answer the question which statement correctly compares the number of protons and electrons in atoms of rubidium (rb) and calcium (ca)?
A. rubidium has more protons and fewer electrons than calcium
b. rubidium has more protons and more elctrons than calcium
c. rubudium has fewer protons and more electrons than calcium
d. rubidum has fewer protons and fewer electrons than calcium

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".