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.
Word equation: magnesium chloride + bromine -> magnesium bromide + chlorine
balance equation: MgCl2 + 2Br -> MgBr2 + 2Cl
1. Double replacement (DR)
2. Decomposition (D)
<h3>Further explanation</h3>
1. Al2(SO4)3 + Ca3(PO4)2 -> 2AIPO4 + 3CaSO4
Double replacement (DR) : there is an ion exchange between two ion compounds in the reactant to form two new ion compounds in the product
General form :
AB + CD -> AD + CB
2. 2NaCIO3 → 2NaCl + 3O2
Decomposition (D) : Reactant breakdown into simpler ones(reverse of combination)
General form :
AB ---> A + B