34 g of O2 are reacted with excess Cs, causing a production of 199 g of Cs2O. What is the percent yield of this reaction?
2 Cs + 02——>Cs2

201cm/s÷5: 18

explanation:

there is no explanation

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.

im not exactly sure but i think its b!