The answer would be D. The only minerals harder than corundum is diamond.
Answer:52M
Explanation:
use S= 1000w/ MV
Here, s= molarity
w= the amount of NaCl
M= the atomic mass of NaCl
V= the volume of solution
According to this formula :
㏑[A] /[Ao] = - Kt
when we have Ao = 0.3 m
and K =0.46 s^-1
t = 20min = 0.2 x 60 =12 s
So by substitution :
㏑[A] / 0.3 = - 0.46 * 12
㏑[A] / 0.3 = - 5.52
by taking e^x for both side of the equation we can get [A]
∴[A] = 0.0012 mol dm^-3
2 Cr + 3 Cl2 ------> 2CrCl3
Na releases 1 electron to be stable
Cl requires 1 electron to be stable
both are ionic bonded to be stable
