Answer: There are 0.000043 moles of melatonin.
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
given mass = 10 mg = 0.01 g
molar mass of 
= 232.28 g
Thus there are 0.000043 moles of melatonin
Answer:
false.
Explanation:
the smallest particle of a element is an atom
The volume of your 0.25 m stock solution that is needed to make 200 ml of 0.010 m NaCl is <u>0.008 L</u>
Concentration is the abundance of a constituent divided by way of the overall volume of an aggregate. several sorts of mathematical descriptions may be outstanding: mass concentration, molar concentration, variety concentration, and extent awareness.
Calculation:-
C₁ = 0.25 M
V₁ = ?
C₂ = 0.010 M
V₂ = 200 ml = 0.2 L
V₁ = C₂V₂/C₁
= 0.010 × 0.2 / 0.25
=<u> 0.008 L</u>
The concentration of a substance is the quantity of solute found in a given amount of solution. Concentrations are normally expressed in terms of molarity, defined because of the variety of moles of solute in 1 L of answer.
The Concentration of an answer is a measure of the quantity of solute that has been dissolved in a given amount of solvent or answer. A concentrated answer is one that has a rather huge quantity of dissolved solute.
Learn more about concentration here:-brainly.com/question/26255204
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