In an aqueous solution of ca(no3)2, which kind of attraction exists between the solute and the solvent?
1) london dispersion force
2) molecule-ion attraction
3) molecule-molecule attraction
4) hydrogen bond

In aqueous solution, Ca(NO₃)₂ dissociates in to Ca²⁺ and NO₃⁻ which both can be attracted to the water molecule since water molecules are very polar.  This means that molecule-ion attractions are present.   
If you can only put 1 answer put 3, but if you can have multiple answers technically London dispersion forces are present as well.  London dispersion forces are in practically everything it is just due to the fact that they are not very strong and are always present means that they are often times ignored.
I hope this helps.  Let me know if anything is unclear.