Consider a diprotic acid with pKa values of 1.60 and 4.50, that is colorless when fully protonated, deep blue when singly deprotonated, and bright red when doubly deprotonated. Assuming that both colored forms have large and approximately equal molar absorptivities, what can be inferred from a solution of the compound that has a faint blue color

it is the most commonly accepted one

(b) which contains higher levels of vitamin b, oranges or spinach?

explanation:

you can eliminate a, c, and d because they are questions based on opinions.

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