KF has NaCl structure.What is the distance between K+ and F- in KF if density is 2.48gm cm-3 ?

Q. $KF$ has $NaCl$ type structure. What is the distance between $K^{+}$ and $F^{-}$ in $KF$ if its density is $2.48$ g cm${}^{-3}$?

Q. $KF$ has $NaCl$ structure. What is the distance (in $A^o$) between $K^{+}$ and $F^{-}$ in $KF$, if density of $KF$ is $2.48$ $gm/c{m}^3$? $[K=39,F=19]$

Q. KF has NaCl type structure. What is the distance (in $\mathring{A}$) between K${}^{+}$ and F${}^{-}$ in KF if density of KF is $2.48$ g cm${}^{-3}$?

Q. KF has a NaCl structure. What is the distance (in pm) between $K^{+}$ and $F^{-}$ in KF if the density is $2.48$ g cm${}^{-3}$ $?