<u>Answer:</u> The volume of NaOH required at the half-equivalence point is 6.21 mL
<u>Explanation:</u>
The chemical equation for the reaction of a weak acid with NaOH follows:

From the equation, we can say that NaOH and weak acid is present in a 1 : 1 ratio.
We are given:
Volume of NaOH required at equivalence point = 12.42 mL
The volume of NaOH required at half-equivalence point will be = 
Hence, the volume of NaOH required at the half-equivalence point is 6.21 mL
I believe it is NaCl(aq) + H2O
Answer : The fugacity in the solution is, 16 bar.
Explanation : Given,
Fugacity of a pure component = 40 bar
Mole fraction of component = 0.4
Lewis-Randall rule : It states that in an ideal solution, the fugacity of a component is directly proportional to the mole fraction of the component in the solution.
Now we have to calculate the fugacity in the solution.
Formula used :

where,
= fugacity in the solution
= fugacity of a pure component
= mole fraction of component
Now put all the give values in the above formula, we get:


Therefore, the fugacity in the solution is, 16 bar.
Answer: Ethyl Ethanoate can be used as a developing solvent. It’s safer.
Explanation:Di ethyl ether should be carefully used because it’s highly flammable and intoxicating when inhaled and can cause explosions because of its high reactivity to air and light.
Photosynthesis. Easy ;) have a nice day