A reaction is definitely not spontaneous when a. DS is positive and DH is negative.
b. DS is negative and DH is positive.
c. DS is negative and DH is negative.
d. DS is positive and DH is positive.

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.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

the objects have the same charge.