Question

Give reasons for the following :
(a). Pickles are stored in glass jars .
(b) Aluminium foils are used to wrap food items .

Answer 1

Dear student, (a)Earthen jars allow the entry of water vapour through the pores in the boundaries and this may spoil the pickle. Glass jars however do not allow the entry of moisture, keeping the pickle fresh.(b)Aluminium is a good conductor of heat, on the other hand its is a bad radiator of heat, therefore when we wrap hot food in the aluminium foil it keep the food warm. Aluminium on reaction with oxygen forms a layer of Al2O3 which renders the metal passive and protects it from further reaction. Hence it is not harmful for us. Thus, aluminium doesn't react with our food therefore we can use it for wrapping purposes. However, we should not pack pickle in aluminium foil as it contains citric acids, which reacts with Al foil and hence can harm us. Regards