The #pragma directive cannot be used in a macro definition because the compiler interprets the number sign character ('#') in the directive to be the stringizing operator (#). The following code example demonstrates how the __pragma keyword can be used in a macro.
The mass number for iodine is 131, which is the sum of the protons  and neutrons. Iodine has 53 protons and 53 electrons, if neutral.  To find how many neutrons iodine has s â¦ ubtract 53, the number of  protons from the mass number of 131. This shows that iodine has 78  neutrons.
4.1 The iodine number is a relative indicator of porosity in an activated carbon. It does not necessarily provide a measure of the carbonâs ability to absorb other species. Iodine number may be used as an approximation of surface area for some types of activated carbons (see Test Method C819).