The answer is to your question is C.7 Hope that is right
(I posted the picture for a ray diagram and the first law of reflection.) The rays show the first law of reflection since everything gets reflected. Look at the picture for more:
Answer: 12.78ml
Explanation:
Given that:
Volume of KOH Vb = ?
Concentration of KOH Cb = 0.149 m
Volume of HBr Va = 17.0 ml
Concentration of HBr Ca = 0.112 m
The equation is as follows
HBr(aq) + KOH(aq) --> KBr(aq) + H2O(l)
and the mole ratio of HBr to KOH is 1:1 (Na, Number of moles of HBr is 1; while Nb, number of moles of KOH is 1)
Then, to get the volume of a 0.149 m potassium hydroxide solution Vb, apply the formula (Ca x Va)/(Cb x Vb) = Na/Nb
(0.112 x 17.0)/(0.149 x Vb) = 1/1
(1.904)/(0.149Vb) = 1/1
cross multiply
1.904 x 1 = 0.149Vb x 1
1.904 = 0.149Vb
divide both sides by 0.149
1.904/0.149 = 0.149Vb/0.149
12.78ml = Vb
Thus, 12.78 ml of potassium hydroxide solution is required.
When the Pka for formic acid = 3.77
and Pka = -㏒ Ka
3.77 = -㏒ Ka
∴Ka = 1.7x10^-4
when Ka = [H+][HCOO-}/[HCOOH]
when we have Ka = 1.7x10^-4 &[HCOOH] = 0.21 m
so by substitution: by using ICE table value
1.7x10^-4 = X*X / (0.21-X)
(1.7x10^-4)*(0.21-X) = X^2 by solving this equation for X
∴X = 0.0059
∴[H+] = 0.0059
∴PH= -㏒ [H+]
= -㏒ 0.0059
= 2.23
Option B
Primary productivity is not limited by time
<u>Explanation:</u>
To ecosystems, the productivity of the primary producers is essential because certain bodies generate energy for different existence bodies. Besides the era, primary production ends in the extension of dissimilar plant biomass to the practice. Consumers acquire their strength from primary producers, unless directly (herbivores, any detritivores), or diffusely.
It depends superimposed on the availability of the sunlight, availability of the nutrients such as nitrogen, iron, phosphorus from the soil and water. The primary productivity of the plant's distinct autotrophs is not restricted by time.
