This says four figures. The 4 figures you should use are 4546 with a peek at 7 to see what effect it will have on the 4 main figures.
45.467 rounds to 45.47
You round the 4th figure up one. You are not concerned about the decimal places in this question.
Molality is obtained by dividing the number of moles of solute by the mass in kilogram of the solvent. None of the dimensions is dependent in temperature. On the other hand, molarity is obtained by dividing the number of moles of solute by the volume in liters of the solution. Volume is temperature dependent.
1 mol = 6.022 x 10²³ atoms
In order to find how many atoms, dimly multiply the amount of moles you have by 6.022 x 10²³ or Avogadro's number.
So you have 1.75 mol CHC1₃ x (6.022x10²³) = 1.05385 x 10²⁴ atoms of CHCl₃
But now you have to round because of the rules of significant figures so you get 1.05 x 10²⁴ atoms of CHCl₃
