Answer:
d. oxygen is a pure substance and rocks are mixtures
it shoudl be : 2Fe(NO3)3 + 3MgSO4 → 3Mg(NO3)2 + Fe2(SO4)3
(the difference is Fe2(SO4)3 has no coefficient)
Answer:
c . a proton
Protons and neutrons have approximately the same mass, about 1.67 × 10−24 grams
Well, you could get the mass as

ad then

, where

is the sea level weight,

the sea level accel.,

the accel. above while

the weight above.
Answer: D.) 25.9%
Explanation:
Dinitrogen pentoxide chemical formular : N2O5
Calculating the molar mass of N2O5
Atomic mass of nitrogen(N) = 14
Atomic mass of oxygen(O) = 16
Therefore molar mass :
N2O5 = (2 × 14) + (5 × 16) = 28 + 80 = 108g/mol
Percentage amount of elements in N205:
NITROGEN (N) :
(Mass of nitrogen / molar mass of N2O5) × 100%
MASS OF NITROGEN = (N2) = 2 × 14 = 28
PERCENT OF NITROGEN : (28/108) × 100%
0.259259 × 100%
= 25.925%
= 25.9%