Which of the following pairs of elements belong to the same group?
a.(h)& (he)
b.(li)& (be)
c.(c)& (pb)
d.(ga)& (ge)

Carbon and Lead make the most sense

Explanation:

None of them are in the same group but carbon and lead are in the same column. Hydrogen is an other non-metal and Helium is a noble gas, Lithium is an Alkali metal and Beryllium is an Alkaline earth metal, Carbon is an other non-metal and Lead is a Post-transition metal, Gallium is Post-transition metal and Germanium is a Metalloid. So none of the pairs are in the same group, but carbon and lead do share the same column.

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.

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