The A horizon is a surface horizon that largely consists of minerals (sand<span>, </span>silt<span>, and </span>clay) and with appreciable amounts of organic matter. This horizon is predominantly the surface layer of many soils in grasslands and agricultural lands.<span>These </span>materials typically<span> accumulate through a process termed illuviation, wherein the </span>materials<span> gradually wash in from the overlying.</span>
Magnesium
<u>Answer:</u> The given amount of iron reacts with 9.0 moles of
and produce 6.0 moles of 
<u>Explanation:</u>
We are given:
Moles of iron = 12.0 moles
The chemical equation for the rusting of iron follows:

By Stoichiometry of the reaction:
4 moles of iron reacts with 3 moles of oxygen gas
So, 12.0 moles of iron will react with =
of oxygen gas
- <u>For iron (III) oxide:</u>
By Stoichiometry of the reaction:
4 moles of iron produces 2 moles of iron (III) oxide
So, 12.0 moles of iron will produce =
of iron (III) oxide
Hence, the given amount of iron reacts with 9.0 moles of
and produce 6.0 moles of 
Aluminium Carbonate on Dissociation produces Aluminium Ions and carbonate Ions as follow,
Al₂(CO₃)₃ → 2 Al⁺³ + 3 CO₃⁻²
Result:
On dissociation Al₂(CO₃)₃ produces FIVE Ions in total. The Ions produced and there number are as follow;
Al⁺² = 2
CO₃⁻² = 3
Answer:
0.23 V.
Explanation:
<em>∵ ΔG° = -RT lnK.</em>
∴ ΔG° = -RTlnK = -(8.314 J/mol)(298 K) ln(7.3 × 10⁷) = - 44.86 x 10³ J/mol.
<em>∵ ΔG° = - nFE°</em>
∴ E° = - ΔG°/nF = - (- 44.86 x 10³ J/mol)/(2 x 96500 s.A/mol) = 0.2324 V ≅ 0.23 V.