We will need to know Avogadro's number and the molar mass of sucrose for this problem to do dimensional analysis.
250g × [tex]\frac{1 mol}{342.297g}[/tex] × [tex]\frac{6.022 * 10^{23} molecules}{1 mol}[/tex] = 4.398 molecules
There are 4.398 sucrose molecules in 250 grams of sucrose.