Question 1199187
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If you add 30mL of 1:400 of Solution A to 270mL of water, what is the resulting concentration?
Select one:
Оа. 0.3%
Ob. 0.025%
Oc. 0.35%
Od. 0.15%
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30 mL of 1:400 of solution A contain  {{{30/401}}} mL = 0.0748 (rounded) mL of the pure substance A.


When we add 270 mL of water, the total volume becomes  30 + 270 = 300 mL, 
with the same amount 0.0748 mL of the pure substance A.


Hence, the final concentration is  {{{0.0748/300}}} = 0.000249333 = 0.00025 (rounded) = 0.025%.
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Solved and fully explained.