(g) How many of all atoms are present in a 10.0 mL sample of ethanol (C2H6O) whose density is 0.889 g/ml?

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.