The Nusselt number is defined as Nu = where Lc is the characteristic length of the surface, h is the convective heat transfer coefficient, and k is the thermal conductivity of the fluid.

Nu = h Lc ÷ k

Explanation: The Nusselt number (Nu) can be defined as the ratio of convective to conductive heat transfer at a boundary in a fluid.

Nu =  Convective Heat Transfer               h Lc

              =      

         Conductive Heat Transfer                  k

Where h  = conductive hear transfer

           Lc = length of the surface

           k   = thermal conductivity of the fluid

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.