All of the elements in a family or group have similar chemical properties. which of the following statements best explains why this is true?

a. the elements in a group have the same number of protons in their nuclei.

b. the elements in a group have similar atomic mass numbers.

c. the elements in a group have the same number of valence electrons.

d. the elements in a group have similar atomic numbers.

What were the success and failures that came to boyle’s excitements?

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

Calculate - analysis of compound composed of iron and oxygen yields 174.86 of fe and 75.14g of o. what is the empirical formula for this compound?