is the amount of space that matter in an object occupies

What color of light must blue light mix with to create white light? a. yellow b. white c. blue d. green

The charge on an electron is 1.60218 × 10−19 c and its mass is 9.10939 × 10−31 kg. how strong a magnetic field must be experienced by the electron if its path is a circle of radius 5.5 cm? answer in units of t.

It is really hard for me right know