A2ml sample was added to a 18 ml diluent in tube 1 which now has a concentration of 300ng/ml. a 2ml of the sample was moved each time into 18ml of diluent to complete 3 dilutions from the first tube, what is the dilution, final dilution and the concentration of tubes 1, 2,3 and 4

288ng/ml

Explanation:

A serial dilution is any dilution where the concentration decreases by the same quantity in each successive step.  

it to 3 rounds of dilutions for the first tube so 3x6=12 so the 300-12=288

answer:

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explanation:

08: 21

read the excerpt from "the tell-tale heart.”

object there was none. passion there was none. i loved the old man. he had never wronged me. he had never given me insult. for his gold i had no desire. i think it was his eye! yes, it was this! he had the eye of a vulture—a pale blue eye, with a film over it. whenever it fell upon me, my blood ran cold; and so by degrees—very gradually—i made up my mind to take the life of the old man, and thus rid myself of the eye forever.  

read the excerpt from "the black cat.”

beneath the pressure of torments such as these, the feeble remnant of the good within me succumbed. evil thoughts became my sole intimates—the darkest and most evil of thoughts. the moodiness of my usual temper increased to hatred of all things and of all mankind; while, from the sudden, frequent, and ungovernable outbursts of a fury to which i now blindly abandoned myself, my uncomplaining wife, alas! was the most usual and the most patient of sufferers.

by revealing the narrator’s deepest thoughts, the author