how to prepare 250ml of 0.1HCI solution from concentrated HCI?

Answer 1

M1= Concentration of you concentrated HCL
V1= The volume you need ( let's say X)
M2= 0.1 HCL
V2= 250ml
Now plug in your value of concentration of your concentrated HCL in the equation below solve X (that gives you how much concentrated HCL you will need to make 250ml of 0.1HCL solution):

V1 = (M2 * V2) / M1

Answer 2

I think you should give the concentration of the concentrated HCl first.

Anway, dilute 0.1 mol of HCl in water. Then remove 250 cm3!