These electron configurations are NOT valid, determine what is wrong with them: 19) 1s2 2s2 2p6 3s2 3p6 4s2 4d10 4p5

20) 1s2 2s2 2p6 3s2 3d5

21) [Ra] 7s2 5f8

22) [Xe]

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-WORTH 15 POINTS-

20. threshold braking in the vehicle's braking system occurs when a. the brake pedal is pushed, heel on floorboard, with full foot pressure. b. the brakes are exerting full braking power, without traction loss. c. the driver begins pushing down the brake pedal, with moderate slowdown. d. the brakes just begin to take hold with a gradual slowdown.

Point charges q1 = 51 µc and q2 = −27 µc are placed 1.0 m apart, with q2 on the right. what is the force (in n) on a third charge q3 = 19 µc placed midway between q1 and q2? (assume the positive direction is to the right. indicate the direction with the sign of your answer.)

What happens when a rubber rod is rubbed with a piece of fur?