how to make up solutions of 0.5% and 0.25% from stock of 5% glucose solution?

Answer 1

Dilute

Use the formula M1*V1=M2*V2
You don't need to do the conversion in mole/lt and ml to liters since the conversion factors cancel out in that equation

So if you want to prepare V2 ml of the final solution you need V1 ml of the stock:

V1= (M2/M1)* V2

So for 0.5% you would have

V1= (0.5/5)*V2= 0.1* V2 ml

and for the 0.25% V1=0.05* V2 ml

Choose a proper volumetric flask or cylinder, add V1 ml (that you calculated) of the 5% solution, add water up to V2, mix and you're done.