IN THE PHYSICAL SCIENCES SECTION: #104) why can the answer not be B? is it because in that case, the oxidation state of Cd would change from +2 to +1? #130) the solutions manual uses the equation x=1/2at^2 to figure out the time the snowball is in the air. however, since we're trying to figure out how long the snowball is in the air during its horizontal flight, how come the manual uses 20 meters (the vertical height of point A) for the value of x? thanks!