An ammonia solution is 6.00 M and the density is 0.950 g/mL. What is the mass/mass percent concentration of NH_3 (17.04 g/mol)? Thank you

##10.8%##
Your strategy here will be to
To make the calculations easier pick a ##1 L## sample of solution. As you know is defined as moles of per liter of solution.
In this case ##1 L## of ##6.00 M## ammonia solution will contain ##6.00## moles of ammonia.
Now you know that this solution has a of ##0.950 g mL^(-1)##. Use it to find the mass of ##1 L## of solution
##1 color(red)(cancel(color(black)(L))) * (10^3color(red)(cancel(color(black)(mL))))/(1color(red)(cancel(color(black)(L)))) * overbrace(0.950 g/(1color(red)(cancel(color(black)(mL)))))^(color(blue)(the given density)) = 950 g##
You know that this sample contains ##6.00## moles of ammonia your solute. Use its molar mass to convert this to grams of solute
##6.00 color(red)(cancel(color(black)(moles NH_3))) * overbrace(17.04 g/(1color(red)(cancel(color(black)(mole NH_3)))))^(color(purple)(the given molar mass)) = 102.24 g##
Now a solution’s mass by mass ##% m/m## tells you how many grams of solute you have in ##100 g## of solution.
##color(blue)(|bar(ul(color(white)(a/a)% m/m = grams of solute / 100 g solutioncolor(white)(a/a)|)))##
In this case you know that ##950 g## of solution contain ##102.24 g## of solute which means that ##100 g## of solution will contain
##100 color(red)(cancel(color(black)(g solution))) * (102.24 g NH_3)/(950color(red)(cancel(color(black)(g solution)))) = 10.8 g NH_3##
Since this is how many grams of ammonia you get per ##100 g## of solution you can say that the solution’s ##%m/m## will be equal to
##% m/m = color(green)(|bar(ul(color(white)(a/a)color(black)(10.8%)color(white)(a/a)|)))##
The answer is rounded to three .