Chemistry / Biochemistry calculation help

You have been provided with the following solutions of a compound (mol. wt. = 200). How many mg would be contained in 50 µl?

(i) 0.2 M
(ii) 300 mM
(iii) 10% (w/v)
(iv) 5g/dL

Any help with working out would be greatly appreciated. Thanks!

i.)

0.2M=moles/volume(L), so solve for moles.

Volume must be converted into L from uL

50uL*(10^-6L/1uL)=50 x 10^-6L

(50 x 10^-6L)*(0.2M)=1 x 10^-5 moles

1 x 10^-5 moles*(200g/mole)=2 x 10^-3 g*(10^3mg/1g)=2mg

ii.)

300mM=0.3M

(50 x 10^-6L)*(0.3M)=1.5 x 10^-5 moles

1.5 x 10^-5 moles*(200g/mole)=3 x 10^-3 g*(10^3mg/1g)=3mg

iii)

10%(w/v)=10g/mL

Convert volume to L

50 x 10^-6L*(10^3mL/1L)=50 x 10^-3mL

10g/mL*(50 x 10^-3mL)*(10^3mg/1g)=500mg

iv)

Convert volume to dL

dL=0.1L

50 x 10^-6L*(1dL/10^-1L)=50 x 10^-5 dL

5g/dL*(50 x 10^-5 dL)*(10^3mg/1g)=2.5mg

Edit: typo

(i) 0.2 M * 50 uL = 10 umole = 0.010 mmole,
then
0.010 mmole * 200 mg/mmole = 2 mg.