How many molecules are there in 122 grams of NO2

This is a two-step question. First, convert the mass of NO2 into the number of moles of NO2. Secondly, quantify the number of moles of NO2 in terms of the number of moles of NO2. The steps and answer are as follows

The answer has been provided to three significant figures to correspond with the number of sig figs given in the mass.

first one is the correct answer

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.