4) would be your correct answer
The ostrich runs 21 N then goes back by 25 S
The displacement is -4 S
21 - 25 = -4
74 is the answer u find it by subtracting the protons(atomic number) from atomic mas, so basically... 127-53 =74 neutrons
In a titration, for an acid to neutralize a base, at the equivalence point, there should be an equal number of moles of H+ and OH-.
Moles of OH- can be found by multiplying the concentration of the base by the volume. (You will need to keep in mind the stoichimetric coefficients if the strong base is Ca(OH)₂, Ba(OH)₂, or Sr(OH)₂.
Moles of OH- = moles of H+
(0.253 M) * 0.005 L = 0.01000 L * c
c = 0.1265 M
The concentration of HBr is 0.127 M.
<span> purity of the substance is usually the main error (for example: water with impurities will have m.p. less than 273K or 0 degree celcius while it's b.p. will be greater than 373K or 100 degree celcius). </span>
<span>-> air/ room temperature (it takes longer to cook in mountains and shorter at beaches) </span>
<span>-> parallax error (error by determining the meniscus of the thermometer) </span>
<span>and many more..</span>
