a person's blood sugar level is usually around 100mg per 100cm^3. if this level falls below 60mg per 100cm^3, insulin can occur. the density of blood is 1.2g cm^-3
what is the percentage by mass of sugar in the blood
i)when the blood sugar level is normal??
ii)during insulin shock??

what is the molar concentration of sugar C6H12O6, in the blood
i)under normal conditions??
ii)during insulin shock??


      Since the density of blood is 1.2 g /cm^3,  then the mass of 100 cm^3of blood is
     1.2 * 100 = 120 gm

1)   So the percentage by mass of sugar in the normal blood level
             =      ( 100mg /120g )  * 100 %
             =      (  1g /120 g) *100 %  = 0.833%

2)   During insulin shock
       the percentage by mass of sugar = (60mg/120g) * 100%
             =       (0.6 g /120g)*100 %  =  0.5%

For molar concentrations, we need molar mass of sugar

Molar mass of C6H12O6 = 6 * 12 +   12 * 1  +  6 * 16 = 180

1)   1 g  of sugar  =  1/180 = 0.00556 moles

                  So molar conc = 0.00556 moles / 100cm^3 = 0.00556/ 0.1L = 0.0556 M

2)   0.6 g of sugar  = 0.6/180 = 0.003333
       
            So molar cond  = 0.003333/ 100 cm^3  = 0.003333/0.1L = 0.03333M   during insulin shock.
   

does it look right now?

100 mg = 0.1 g!!!
60 mg = 0.06 g!!!
and all results show 1000 % error

1)   0.1/120 x 100 = 0.083
so 0.08%

2)  0.06/120 x 100 = 0.05%

1) 0.1/180= 0.0005

2)0.06/180= 0.0003
how about now? r the calculation right?

Two significant figures would be better

Yup.  So you'd be better off with the following answers:

1):  8.3x10^-2%.
2):  5.0x10^-2%.

1):  5.6x10^-3 Molar.
2):  3.3x10^-3 Molar.

Two sig-figs is proper because of all the numbers you were given, it is to be assumed that the density of blood (1.2 g/mL) has the least number (2).

As an aside, the onset of insulin shock doesn't really kick in until blood sugar levels get much lower.  The first signs of hypoglycemia may kick in at around 60 mg/dL, but full blown loss of conciousness really doesn't kick in until around the mid teens.  I've been fully concious with a blood sugar of around 27 mg/dL, and many times with a BSL even lower.  It's just that at that low of a level muscle coordination, reaction time, and a lot of other nervous system functions become hampered.  (In really the same manner as it does with ethanol intoxication).