Which of the following is a true statement? A. If one mole of 39K has a mass of 39.1 grams, the mass of one atom of 39K is 39.1x10^-23 grams.
В. If one atom of 12C has a mass of 12.0 amu, one mole of 12C atoms has a mass of 12 x 6.02x10^23 grams.
C. If one atom of 223Fr has a mass of 223.0 amu, one mole of 223Fr has a mass of 223.0x10^23 amu.
D. If one atom of 1271 has a mass of 126.9 amu, one mole of 1271 has a mass of 126.9 grams.

d.) circle motion requires a force to give it a centripetal acceleration.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2