The first thing you do before performing anything in the laboratory is to read the procedure and prepare the materials needed. Next, if you already have the solution where you are supposed to take your 20 mL sample, then have it near you. Then, prepare a volumetric flask (750 mL) and a 20-mL pipette. Wash the pipette 3 times with the sample solution. If your diluent is water, wash the flask 3 times with water. Now, get 20 mL of sample from your parent solution, then add it to the flask (previously washed with water). Finally, add water until the mark in the flask and make sure that the water added is up to the mark based on the lower meniscus reading to be accurate in the amount inside the flask. <span />
The correct answer among the choices given is option B. Radioisotopes are isotopes that emit radiation because they have unstable nuclei. These are radioactive isotopes of an element. They are defined as atoms that contain an unstable combination of neutrons and protons.
Answer:
D H2PO4– + HPO42–
Explanation:
The acid dissociation constant for 
are 
respectively.
The reason while option D is the best answer is that, the value of pKa for both
lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.
Using Henderson-Hasselbach equation:
Answer:
the anserw should be 665KJ
Answer:
6.319857 * 10 to the power 7
