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
Reactivity is the name your looking for I believe.
A molecule of hydrogen is formed by two hydrogen atoms, that is a fact.
How does it work? When two atoms, known as "diatomic" pair with another in a bond known non-polar covalent bonds. Where they equally share electrons. A Hydrogen atoms needs 1 more electrons to fill its first shell fully and have a full valence shell. So if two H's share their electrons, they'll both have a full V-Shell!
That's the basics of both the H-H bond and all the other diatomic bonds as well.
According to Arrhenius theory of acid and base, Acids are those substances which when dissolved in water produces protons, while, Bases are those substances which when dissolved in water produces Hydroxyl Ions.
Example of Arrhenius Bases:
NaOH ₍s₎ → Na⁺ ₍aq₎ + ⁻OH ₍aq₎
LiOH ₍s₎ → Li⁺ ₍aq₎ + ⁻OH ₍aq₎
Result:
The only negative ion produced in water when Arrhenius Base is dissolved is ⁻OH (Hydroxyl Ion).
<u>Answer:</u> The molecular weight of protein is 
<u>Explanation:</u>
To calculate the concentration of solute, we use the equation for osmotic pressure, which is:
or,
where,
= Osmotic pressure of the solution = 0.0861 atm
i = Van't hoff factor = 1 (for non-electrolytes)
= mass of protein = 400 mg = 0.4 g (Conversion factor: 1 g = 1000 mg)
= molar mass of protein = ?
= Volume of solution = 5.00 mL
R = Gas constant = 
T = temperature of the solution = ![25^oC=[25+273]K=298K](https://tex.z-dn.net/?f=25%5EoC%3D%5B25%2B273%5DK%3D298K)
Putting values in above equation, we get:
Hence, the molecular weight of protein is
