Phosphoric acid is neutralized by potassium hydroxide according to the following reaction: KOH (aq) + H3PO4 (aq) → K3PO4 (aq) + H2O (1)
What is the concentration of a phosphoric acid solution if 25.0 mL are exactly neutralized by 20.0 mL of 2.000 M KOH solution?

Balance the reaction first:

3KOH + H3PO4 —> K3PO4 + 3H2O

So for every mol of H3PO4, you need 3 mol of OH- to fully neutralize the acid, since H3PO4 is polyprotic.

0.0200 L KOH • (2.000 mol KOH / L KOH) • (1 mol H3PO4 / 3 mol KOH) = 0.0133 mol H3PO4

Divide this by the volume of H3PO4 to get the concentration.

0.0133 mol H3PO4 / 0.0250 L = 0.532 M H3PO4

Mescarinic and Nicotinic

Explanation:

Postganglionic fibers can be present in both sympathetic and parasympathetic divisions, their main difference resides in how in the sympathetic division the postganglionic fibers are adrenergic and use norepinephrine (noradrenalin) as a neurotransmitter, in the parasympathetic division, on the other hand, fibers are cholinergic and use acetylcholine as a neurotransmitter, the postganglionic neurons of sweat glands release acetylcholine for the activation of muscarinic receptors, another kind of receptor for acetylcholine are nicotinic receptors that act as transmembrane sodium/potassium channels, while muscarinic receptors need to act through intracellular proteins.

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