Answer:
2000 millimoles of AlCl₃ 
Explanation:
From the question given above, the following data were obtained:
Volume of solution = 1.8 L
Molarity of solution = 1.1 mol /L 
Millmole of AlCl₃ =?
Next, we shall determine the number of mole of AlCl₃ in the solution.
This can be obtained as follow:
Volume of solution = 1.8 L
Molarity of AlCl₃ solution = 1.1 mol /L 
Number of mole of AlCl₃ =?
Molarity = mole /Volume 
1.1 = Number of mole of AlCl₃ / 1.8
Cross multiply 
Number of mole of AlCl₃ = 1.1 × 1.8
Number of mole of AlCl₃ = 1.98 moles 
Finally, we shall convert 1.98 moles to millimoles. This can be obtained as follow:
1 mole = 1000 millimoles
Therefore, 
1.98 mole = 1.98 mole × 1000 millimoles / 1 mole 
1.98 mole = 1980 millimoles 
1.98 mole ≈ 2000 millimoles
Thus, the chemist added 2000 millimoles of AlCl₃