Question

Which of the following elements will form acidic oxide?
A.\[{\text{Na}}\]
B.\[{\text{Si}}\]
C.\[{\text{Mg}}\]
D.\[{\text{P}}\]

Answer 1

Hint:Generally metals form basic oxides especially alkaline and alkaline earth metals. The non metals on the right side of the periodic table forms acidic oxide.

Complete step by step answer:
Nature of oxides whether it is acidic or basic can be found after treatment of the oxide with water. Generally the metal oxides on treatment with water form metal hydroxides which are basic in nature. For example when the oxide of sodium metal that is sodium oxide is treated with water sodium hydroxide forms and which is a well known base. This proves the basicity of metal oxide.Similarly when a non metal oxide is treated with water then formation of oxyacids occurs which are acidic in nature. Carbon is a non metal and hence its oxide that is carbon dioxide when dissolved in water form of carbonic acid which is an acid. So oxides of non metals are acidic in nature. The S block elements such as sodium and magnesium are metals and their oxides are basic in nature and the metals of p block that is Phosphorus and sulphur have acidic oxides.

Hence, the correct option is B and D.

Note:
Some oxides are also neutral oxide such as carbon monoxide and nitric oxide. While some of the oxides also show amphoteric character, that is they are neither acidic nor basic. The amphoteric oxides are zinc oxide, Aluminium oxide and arsenic oxide and gallium oxide. While moving from left to right in a period acidic nature increases and down the group the acidic nature decreases.