D, obviously. All living things are made of one or more cells, therefore non-living things aren’t made of cells
Answer:
28.58 g of NaOH
Explanation:
The question is incomplete. The missing part is:
<em>"Calculate the mass of sodium hydroxide that the chemist must weigh out in the second step"</em>
To do this, we need to know how much of the base we have to weight to prepare this solution.
First we know that is a sodium hydroxide aqueous solution so, this will dissociate in the ions:
NaOH -------> Na⁺ + OH⁻
As NaOH is a strong base, it will dissociate completely in solution, so, starting with the pH we need to calculate the concentration of OH⁻.
This can be done with the following expression:
14 = pH + pOH
and pOH = -log[OH⁻]
So all we have to do is solve for pOH and then, [OH⁻]. To get the pOH:
pOH = 14 - 13.9 = 0.10
[OH⁻] = 10⁽⁻⁰°¹⁰⁾
[OH⁻] = 0.794 M
Now that we have the concentration, let's calculate the moles that needs to be in the 900 mL:
n = M * V
n = 0.794 * 0.9
n = 0.7146 moles
Finally, to get the mass that need to be weighted, we need to molecular mass of NaOH which is 39.997 g/mol so the mass:
m = 39.997 * 0.7146
<h2>
m = 28.58 g</h2>
There's two sig figs: the 1 and the zero. The 10^-2 contributes no sig figs.
<span>The correct answer among
the choices given is the last option. Galaxies are classified according to
their shapes or visual morphology. There three main types of galaxies
currently. They are the elliptical, spiral and irregular. Elliptical galaxies
are like a spheroid or an elongated sphere. Spiral galaxies are characterized
and distinguished by having a bulge, a disk and a halo. Lastly, irregular
galaxies do not have regular or symmetrical shape.</span>
