In a cold pack, which type of reaction draws heat from the surroundings?

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!

To calculate percent by mass, use the equation below: calculate the percent by mass of each element. %n = % %h = % %o = %

Adirect relationship can be represented by: a curve a pie chart