In alkanes with three or fewer carbon atoms, a. the chains can be straight or branched.
b. usually one but sometimes more than one molecular structure is possible.
c. structural isomers exist.
d. only one molecular structure is possible.

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.