Elements of Groups 16, 17 and 18 — Chemistry STD 12 Science — Question

Oxides are binary compounds formed by the chemical combination of a substance metal or a non-metal with oxygen.
The binary compounds of oxygen with other elements are called oxides. We have studied that oxygen combines with metals and non-metals to form their respective binary oxides. In these oxides, the oxidation state of oxygen is always –2.
Simple oxides
The simple oxides behave as acids or bases according to their dissociation in water. On the basis of acid-base characteristics, the oxides may be classified into the following four types :
1. Acidic oxides: The oxides which combine with water to give acids are called acidic oxides. These are generally the oxides of non-metals such as carbon, sulphur, phosphorus, etc. For example
$SO _2+ H _2 O \rightarrow H _2 SO _3$ Sulphurous Acid
$CO _2+ H _2 O \rightarrow H _2 CO _3$ Carbonic acid
2. Basic oxides :
The oxides which combine with water to give basic solution are called basic oxides. These are mostly the oxides of metals. For example Na2O +H2O→2NaOH
3. Amphoteric oxides : The oxides which show acidic as well as basic character are called amphoteric oxides. For example,
$Al 2 O 3( s )+6 HCl ( aq )+9 H 2 O \rightarrow 2[ Al ( H 2 O ) 6] 3+$
(Basic)
(aq) +6 Cl-(aq)
$Al _2 O _{3(s)}+6 NaOH _{a q} \rightarrow$
(Basic)
$2 Na _3\left[ Al ( OH )_6\right]_{a q}$
4. Neutral Oxides:
Some compounds react with oxygen to form oxides which do not exhibit acidic nor basic characteristics. Such compounds are called as neutral compounds of oxygen.
Example: NO, CO.