A starch molecule contains 500 glucose units - VCE - SSCE Chemistry - Question 16 - 2011 - Paper 1

To find the molar mass of the starch molecule, we need to multiply the number of glucose units by the molar mass of one glucose unit. The calculation is as follows:

$$ext{Molar Mass of Starch} = ext{Number of Glucose Units} imes ext{Molar Mass of Glucose}$$

Substituting the values:

$$ext{Molar Mass of Starch} = 500 imes 180 ext{ g mol}^{-1}$$

Calculating this gives:

$$ext{Molar Mass of Starch} = 90000 ext{ g mol}^{-1}$$

Thus, the molar mass of the starch molecule is 90000 g mol⁻¹, which corresponds to option C.