Radical, in chemistry, molecule that contains at least one unpaired electron. Most molecules contain even numbers of electrons, and the covalent chemical bonds holding the atoms together within a molecule normally consist of pairs of electrons jointly shared by the atoms linked by the bond.
Their prey would decrease
The two reason behind the invalidity of flame test are false positive and false negative.
while performing the flame test you must have to be accurate otherwise you will get false results may be positive for some element or may be negative in case the element is present. The main reason to get the false positive and false negative is the presence and contamination of sodium.
A measure of thermal energy transferred between two different bodies at different temperatures would be the correct answer. So, the third option.