6) How many valence electrons does an atom of Cu possess?
ОА) 2
Ов) 9
Ос) 11
OD) 3
OE) 1

Astudent carefully transfers 30 g of water and 30 g of alcohol in a glass tube, forming two layers and filling the tube completely. after sealing the tube, the student mixes the solutions, and notices a bubble that forms in the tube. what is the mass of the contents in the glass tube after mixing?

Wind and moving water provide energy. chemical mechanical thermal none of the above

How many significant figures are in the following numbers ? a. 0.0002030 b. 2.000 c. 2.008900 d. 145.00