Answer:
9.28
Explanation:
pOH refers to a measure of hydroxide ions concentration. pOH tells about the alkalinity of a solution. If pOH is less than 7 then aqueous solutions are alkaline, acidic if pOH is greater than 7 and neutral if pOH is equal to 7.
Concentration of the hydroxide ions = 1.9 x 10-5 M
pH = 
pOH = 14 - pH
=14 - 4.72 = 9.28
<u />C. Water is an inexhaustible energy resource among these options. Coal, oil, and natural gas we can run of, but for the foreseeable future, there will always be water.
Given: wavelength of Nitrogen laser (∧) = 337.1 nm = 337.1 X 10^-9 m
We know that, Energy of photon (E) = hc/∧ = hv
where, v = frequency of photon and c = speed of light = 3 X 10^8 m/s
Thus, v = c/∧ = (3 X 10^8)/ (337.1 X 10^-9) = 8.899 X 10^14 s-1.
Answer: F<span>requency of nitrogen laser = </span>8.899 X 10^14 s-1.
NaBr + CaF2 → NaF + CaBr2 What coefficients are needed to balance the chemical equation? A) 1,1,1,1 B) 1,2,1,2 C) 1,2,2,1 D) 2,1
elena-s [515]
D.
2NaBr + CaF2 --> 2NaF + CaBr2 gives you:
2Na 2Na
2Br 2F
1Ca 1Ca
2F 2Br
This is balanced.
