Which of the following statements about oxides of metals and non metals is correct according to general periodic trends?

Introduction / Context:
Oxides are compounds formed when elements combine with oxygen. Their behaviour in water and with acids or bases depends strongly on whether the parent element is a metal or a non metal. Recognising the general patterns for metal oxides and non metal oxides is essential for predicting acid base reactions, understanding environmental issues like acid rain and answering basic periodic table questions. This question asks which statement correctly describes the typical behaviour of non metal oxides with respect to acidity.

Given Data / Assumptions:

• We are considering simple oxides of typical metals and non metals.
• Metal oxides such as Na2O, CaO and MgO are often basic oxides.
• Non metal oxides such as CO2, SO2 and P2O5 are often acidic oxides.
• We are focusing on general trends, not rare exceptions.
• Acidic oxides form acids when dissolved in water, while basic oxides form bases.

Concept / Approach:
Most metal oxides are basic; they react with water to form metal hydroxides, which are bases, and they neutralise acids. In contrast, many non metal oxides are acidic; they react with water to form oxyacids and neutralise bases. For example, CO2 reacts with water to form carbonic acid, and SO3 reacts with water to form sulfuric acid. A few oxides are amphoteric or neutral, but the general rule in school chemistry is that non metal oxides are acidic. The correct approach is to identify the statement consistent with this rule, which is that most non metal oxides are acidic in water.

Step-by-Step Solution:
Step 1: Consider examples of non metal oxides such as CO2, SO2, SO3 and P2O5. These all form acids when dissolved in water. Step 2: Carbon dioxide and water give carbonic acid, H2CO3. Sulfur dioxide and water give sulfurous acid, H2SO3, while sulfur trioxide and water give sulfuric acid, H2SO4. Step 3: These reactions show that non metal oxides are generally acidic in nature. Step 4: Metal oxides such as Na2O and CaO react with water to produce bases like NaOH and Ca(OH)2, which turn red litmus blue and neutralise acids, showing basic character. Step 5: Therefore, it is incorrect to say that metal oxides are acidic in general, and it is also wrong to claim that all oxides are neutral. Step 6: Among the options, the statement that most oxides of non metals are acidic in water is the correct general rule.

Verification / Alternative check:
Laboratory tests confirm these trends. Passing CO2 through water and testing with litmus shows that the resulting solution is acidic. Similarly, solutions prepared from sulfur dioxide show acidic behaviour. Metal oxides such as sodium oxide, when dissolved or reacted with water, produce strongly basic solutions. Environmental chemistry also supports this pattern, since many non metal oxide emissions, such as SO2 and NO2, contribute to acid rain by forming acids in the atmosphere. Textbooks summarise these observations by stating that metal oxides are usually basic and non metal oxides are usually acidic, with a few amphoteric exceptions like aluminium oxide.

Why Other Options Are Wrong:
Option A claims that most oxides of non metals are basic, which is the opposite of the observed trend. Option C states that most oxides of metals are acidic, which contradicts the fact that metal oxides usually form bases and neutralise acids. Option D claims that all oxides are neutral, which is clearly false because many oxides form acids or bases in water. Option E says that all the statements are correct, which cannot be true since options A, C and D are incorrect. Only option B accurately states that most oxides of non metals are acidic in water.

Common Pitfalls:
Students sometimes memorise that metal equals basic and non metal equals acidic but then mix up which oxides correspond to which behaviour. Another issue is forgetting that there are exceptions such as amphoteric oxides, but examination questions like this one usually ask for the general rule. To avoid confusion, associate metal oxides with basic solutions and non metal oxides with acidic solutions, and remember that these patterns are especially strong among s block metals and p block non metals.

Final Answer:
The correct statement is that Most oxides of non metals are acidic in water, forming acids when dissolved and neutralising bases.