What characteristic of an atom always varies among atoms of different elements?

Asap! how do you lengthen a pattern piece? (family and consumer science, sewing)

Astudent completes a titration by adding 12.0 milliliters of naoh(aq) of unknown concentration to 16.0 milliliters of 0.15 m hcl(aq). what is the molar concentration of the naoh(aq)? 1)5.0 m 2)0.20 m 3)0.11 m 4)1.1 m

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.