The number of atoms in vitamin d and the valence number of each atoms?

The seven sisters, seven stars located more than 400 light-years away in the taurus constellation can be seen here with venus and another constellation, orion. the seven stars stay grouped together but seem to move, like the planet venus. why do stars seem to move like planets in the night sky?

Why do different substances have diffrent properties

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?