B. When scientific understanding changes.
Ain't is the correct answer
Answer:
6⅔ shifts
Explanation:
From the question given:
A shift = 4 hours
Pay = $8.25 per hour
Next, we shall determine the number of hours that will result in a pay of $220. This can be obtained as follow:
$8.25 = 1 hour
Therefore,
$220 = $220 × 1 hour / $8.25
$220 = 220/8.25 hours.
$220 = 80/3 hours
$220 = 26⅔ hours
Therefore, it will take 26⅔ hours to receive a pay of $220.
Finally, we shall determine the number of shifts in 26⅔ hours. This can be obtained as follow:
4 hours = 1 shift
Therefore,
26⅔ hours = 26⅔ ÷ 4
26⅔ hours = 80/3 × 1/4
26⅔ hours = 80/12
26⅔ hours = 20/3
26⅔ hours = 6⅔ shifts
Therefore, she will work 6⅔ shifts in order to receive a pay of $220
Answer:
ΔH°rxn = -47 kJ
Explanation:
Using Hess´s law for the reaction:
3 Fe2O3(s) + CO(g) → 2 Fe3O4(s) + CO2(g) ,
the ΔH°rxn will be given by the expression:
ΔH°rxn kJ = 2ΔHºf(Fe3O4) + ΔHºf(CO2) - ( 3ΔHºf(Fe2O3) + ΔHºf(CO) )
= 2(-1118) + (-394) - ( 3( -824 ) + ( -111 ) )
= - 47 kJ
Use higher concentration of acid to produce 2 moles of hydrogen to form water
