Answer: D) the iconic compound calcium fluoride (CaF₂)
Explanation:
\(\Delta T_f=i\times k_f\times m\)
where,
\(\DeltaT_f\) = change in freezing point
i= vant hoff factor
\(k_f\) = freezing point constant
m = molality
A) the molecular compound sucrose (C₁₂H₂₂O₁₁)
: For non electrolytes like sucrose, vant hoff factor is 1.
B) the iconic compound magnesium sulfate (MgSO₄): For electrolytes, vant hoff factor is equal to the number of ions it produce on dissociation.
\(MgSO_4\rightarrow Mg^{2+}+SO_4^{2-}\) Thus i= 2
C) the iconic lithium chloride (LiCI):
\(LiCl\rightarrow Li^++Cl^-\), thus i=2.
Thus 1% produces most ions and thus lowers the freezing point to maximum.
D) the iconic compound calcium fluoride(CaF₂):
\(CaF_2\rightarrow Ca^{2+}+2F^-\), thus i=3.
Thus the compound with highest value of i, will depress the freezing point to maximum.
