In three moles of ethane $\left({\mathrm{C}}_2{\mathrm{H}}_6\right)$, calculate the following:

The number of molecules of ethane. 

Express the following in the scientific notation:

$6.0012$

In a reaction $\mathrm{A}+{\mathrm{B}}_2\to {\mathrm{AB}}_2$
Identify the limiting reagent, if any, in the following reaction mixture.
$5$ mole $\mathrm{A}+2.5$ mole $\mathrm{B}$

Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical reaction:
${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\to 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$
(i) Calculate the mass of ammonia produced if $2.00\times 10^3 \mathrm{g}$ dinitrogen reacts with $1.00\times 10^3 \mathrm{g}$ of dihydrogen.

(ii) Will any of the two reactants remain unreacted?

(iii) If yes, which one and what would be its mass?