Answer:
I cannot give you all the answer but I can help you to solve those.
Explanation:
The first question:
How many grams are there in 7.5×
molecules of 
?
So we need to find the molecular mass first, use your periodic table,
And then we can find out 2+32+16×4=98 g/mol
Then, we need to find how many moles, by using Avogadro's constant:
Avogadro's constant: 1 mole = 6.02×
∴
=1.25 mol(2d.p.)
Lastly, find the grams using the formula 
m=Mn
m=1.25*98
m=122.5g
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In conclusion, use those formula to help you:
(which M = molecular mass(atomic mass) m=mass of the substance and n = moles)
Avogadro's constant: 
Answer:
Explanation:
there are a certain amount of atoms
Answer:
Explanation:
As one moves down the vertical groupings of elements on the periodic table, it is evident that new shells are being added from top to down.
An atomic orbital is the region of space surrounding the nucleus where there is a high probability of finding an electron.
Down a group, the atomic radius increases as more shells are added to an atom.
Answer:
<em>The correct option is the structure in the option D. </em>
Explanation:
Ammonia contains a single nitrogen atom bonded to three hydrogen atoms.
The structure present in option A shows a single nitrogen atom bonded with a single hydrogen atom hence it is not correct.
The structure in option B shows a nitrogen atom bonded to four hydrogen atoms hence it is also not correct.
The structure in option C shows a nitrogen atom bonded to two hydrogen atoms hence it is also not correct.
The structure in option D shows a nitrogen atom bonded to three hydrogen atoms which is the correct structure of ammonia (NH3).
