In this lab, you determined the volume of water delivered using a mechanical pipet set to deliver 4.00 mL. You could have carried out the same procedure delivering 4-ml portions of water using a small graduated cylinder. A typical result for such a measurement is the following (result of five replicate measurements): Graduated cylinder Average: 3.92 mL St. Dev: 0.11 mL (2pts) a. Calculate the percent error for the graduated cylinder method described above, assuming the intended volume was 4.00 mL. (2pts) b. Calculate the CV for the graduated cylinder method described above, assuming the intended volume was 4.00 mL. (2pts) c. Compare the results for the graduated cylinder (from above) and your result using a mechanical pipet. Which method of delivery (graduated cylinder or pipet) is more accurate

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.