Which of the following statements about valence electrons and the periodic table is true?
a) the number of valence electrons decreases from left to right across each period. b) the number of valence electrons increases from top to bottom within each group.
c) all of the elements in group 9 have nine valence electrons.
d) elements with the most valence electrons are in group 18.

A50.0-n box is sliding on a rough horizontal floor, and the only horizontal force acting on it is friction. you observe that at one instant the box is sliding to the right at and that it stops in 2.25 s with uniform acceleration. what magnitude force does friction exert on this box

Amass attached to a spring is displaced from its equilibrium position by 5cm and released. the system then oscillates in simple harmonic motion with a period of 1s. if that same mass–spring system is displaced from equilibrium by 10cm instead, what will its period be in this case? a mass attached to a spring is displaced from its equilibrium position by and released. the system then oscillates in simple harmonic motion with a period of . if that same mass–spring system is displaced from equilibrium by instead, what will its period be in this case? a) 0.5sb) 2sc) 1sd) 1.4s

Which of the following statement is false