Answer:
This reactivity order reflects both the strength of the C–X bond, and the stability of X(–) as a leaving group, and leads to the general conclusion that alkyl iodides are the most reactive members of this functional class.
Opposite pairs form ionic bonds, due to this the answer is D - Li and Br; They have unlike charges.
Many homeowners treat their lawns with CaCO3(s) to reduce
the acidity of the soil. The net ionic equation for the reaction of CaCO3(s)
with a strong acid, HCl (I chose HCl because it is a strong acid) is CaCO3(s) +2
HCl(aq) → CaCl2(s) + H2O(aq) + CO2(g).