Which TWO observations are evidence that a chemical change is happening? A. A yellow liquid forms as a yellow solid is slowly heated.

B. Bubbles of gas are released when a solid is combined with a liquid.

C. Solid crystals form as the temperature of a liquid is lowered.

D. Light and heat are given off after a spark ignites a substance.

Compared with the freezing-point depression of a 0.01 m c6h12o6 solution, the freezing-point depression of a 0.01 m nacl solution is

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons

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!