Hi all.. I have a question regarding the density of a solution. In my lab manual, it said to use 50 mL of 20% NaOH solution I have problem of understanding whether the 20% is the molar or mass or volume basis.. It doesn't state anything else in there.. what does it usually means? And i think i need density to find the number of moles of NaOH in this solution.. or am i wrong? Thanks in advance!