A student adds a few drops of ethanoic acid to test tubes X, Y and Z containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate, respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding ethanoic acid in each one of them, in which of the test tube or test tubes the flame will be extinguished? (A) X and Y (B) Y and Z (C) X and Z (D) only Z



The answer will be D)only Z
In case 1 the formula will be; CH3COOH+NaCl -----------------------> NO REACTION (CH3COOH is a weak acid, whereas NaCl is a neutral ion pair so it will have no effect)
So flame will not get extinguished 
In case 2 the formula will be; CH3COOH + NaOH------------------> CH3COONa+H2O
So flame will not get extinguished as H2O cannot extinguish a flame without direct contact
It case 3 the formula will be; CH3COOH+Na2CO3----------------->CH3COONa+H2O+CO2 
Thus the flame will be extinguished as CO2 does not support combustion