can someone please help me with this chemistry equation, i'll give you a 5-star rating, a heart, and the brainliest answer​

I'm learning about the periodic tables and what each subject's configuration is. for example, hydrogen is 1s^1, but i don't understand how you get that. can someone me understand how to figure out how to figure this out? sorry if the question makes no sense, but it would really a lot if you could me understand! you so much if you can!

Mercury metal is poured into a graduated cylinder that holds exactly 22.5 ml the mercury used to fill the cylinder mass in 306.0 g from this information calculate the density of mercury

What is bromine+calcium iodide--> calcium bromide +iodine balanced