The dilution factor : 100
Further explanation
The dilution factor(DF) : ratio of concentration of stock solution and diluted solution or ratio of the volume of final solution to the initial volume from stock solution
From equation of dilution :
M₁V₁=M₂V₂
![\tt DF=(M_1)/(M_2)=(V_2)/(V_1)](https://img.qammunity.org/2021/formulas/chemistry/college/xtcwhsu9674iho9g4daif0ceiwxx46e6us.png)
Volume of aliquot = 0.1 ml
Volume of diluent = 9.9 ml
So final volume :
![\tt V_f(final~volume)=volume~aliquot+volume~diluent\\\\V_f=0.1+9.9=10~ml](https://img.qammunity.org/2021/formulas/chemistry/college/zhw8v216ojmf32ufa8jxxwe87cy2io3ebq.png)
The dilution factor (DF) :
![\tt D_f=(V_f)/(V_i)\\\\D_f=(10)/(0.1)=100](https://img.qammunity.org/2021/formulas/chemistry/college/zc73kapdjwvviuqntfsp9v5rwpcgwhx3zq.png)