Can you show the question that goes with those answer pls
Answer:
Au
Explanation:
For the density of a face-centered cubic:

where
= molar mass of the compound
avogadro's constant
the volume of a unit cell
Given that:
Density
= 19.30 g/cm³
a = 0.408 nm
a = 
a = 
∴



Thus, the molar mass of 197.37 g/mol element is Gold (Au).
<span>The magnetic field of the Earth serves a useful purpose in deflecting Solar radiation. Without the magnetic field there is much more charged-particle radiation striking the surface. The auroras would occur everywhere instead of at the magnetic poles. Compass needles wouldn't work, and then they would flip direction.. The magnetic field IS DECREASING and could go to zero and reverse sometime in the next few tens-of-thousands of years.</span>
One of the best buffer choice for pH = 8.0 is Tris with Ka value of 6.3 x 10^-9.
To support this answer, we first calculate for the pKa value as the negative logarithm of the Ka value:
pKa = -log Ka
For Tris, which is an abbreviation for 2-Amino-2-hydroxymethyl-propane-1,3 -diol and has a Ka value of 6.3 x 10^-9, the pKa is
pKa = -log Ka
= -log (6.3x10^-9)
= 8.2
We know that buffers work best when pH is equal to pKa:
pKa = 8.2 = pH
Therefore Tris would be a best buffer at pH = 8.0.
I believe the answer is C