Which of these pairs of elements have the same number of valence electrons? answer quick

hydrogen (h) and helium (he)

sodium (na) and potassium (k)

carbon (c) and oxygen (o)

boron (b) and beryllium (be)

The electronic structure or chlorine is 2.8.7 what is the electronic structure of fluorine?

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?

Will mark as brainliest how does a catapult increase the trajectory of an object? ps. answer as if u were a 5th grader