First let us calculate for the number of moles needed:
moles NaOH = 0.125 M * 0.500 L = 0.0625 mol
The molar mass of NaOH is 40 g/mol, hence the mass is:
mass NaOH = 0.0625 mol * 40 g/mol
<span>mass NaOH = 2.5 grams</span>
Answer:
The answer should be 40.3044 g/mol
These 2 isotopes are all of bromine that is naturally found (their percentages add up to 100%). In order to calculate the mean atomic mass, we can use the following calculation:

. This yields an average atomic mass of 79.903 amu. This procedure is general; whenever we have many types F of a specific genre G, the mean of the genre G can be calculated by:

where

is the proportion of type i in the genre G. In this example, Br79 and Br81 are the 2 types and the genre is Bromine.
PH=-lg[H⁺]
pH=-lg(1.0*10⁻¹¹)=11
pH=11
Answer:
MOLAR MASS=12+4
=16 gmol^-1
number of moles=Mass/ molar mass
=0.900g/16gmol^-1
=0.05625 mol
the answer is first option