### How much is 200mm in dm?

mm means "millimeters" dm means "decimeters" Note that "milli-" means "thousandths of a unit" and "deci-" means "tenths of a unit". This means: 1 m = 1000 mm 1 m = 10 dm Combine these conversions altogether to get: 1 mm = 1.0 x 10-3 m = 1.0 x 10-2 dm Another way of interpreting this is 1 dm = 100 mm. Therefore, 200 mm is 2 dm.

### The volume of a typical bacterial cell is on the order of 1.0 micrometers cubed. At pH 7.0 how many hydrogen ions are contained inside a bacterial cell?

pH=-log10[H+]=7 so [H+]=10^-7M molar concentration (M) = number of moles / dm^3 so number of moles of H+=10^-7 mol/dm^3 * volume in dm^3 1 dm^3 = (0.1m)^3 = 10^-3 m^3 1 um^3 = (10^-6 m)^3 = 10^-18 m^3 so volume in dm^3 = 10^-15 dm^3 therefore the number of moles of H+=10^-22 there are 6.022*10^23 molecules per mole so there are about 60 H+ ions in the bacterial cell at pH 7