Question

The acidic character of the oxides increases in the order:

• A. Na$_2$O $<$ MgO $<$ Al$_2$O$_3$ $<$ SiO$_2$ $<$ P$_2$O$_5$
• B. Na$_2$O $<$ Al$_2$O$_3$ $<$ MgO $<$ SiO$_2$ $<$ P$_2$O$_5$
• C. P$_2$O$_5$ $<$ SiO$_2$ $<$ Al$_2$O$_3$ $<$ MgO $<$ Na$_2$O
• D. Al$_2$O$_3$ $<$ SiO$_2$ $<$ MgO $<$ P$_2$O$_5$ $<$ Na$_2$O

Hint:

Acidic nature increases across a period and decreases down a group. Metal oxides are basic; non-metal oxides are acidic.

Answer 1

The Correct Option is A

To determine the order of acidic character for the given oxides, we need to consider their positions in the periodic table and their properties: 

1. Na$_2$O (Sodium Oxide): This is a basic oxide because sodium is a metal located in Group 1 of the periodic table, which typically forms basic oxides.
2. MgO (Magnesium Oxide): Also a basic oxide but less basic than Na$_2$O. Magnesium is an alkaline earth metal from Group 2.
3. Al$_2$O$_3$ (Aluminum Oxide): This is an amphoteric oxide. Aluminum is a metalloid and can form oxides that exhibit both acidic and basic properties.
4. SiO$_2$ (Silicon Dioxide): This oxide is acidic. Silicon is a metalloid from Group 14 and forms acidic oxides like SiO$_2$.
5. P$_2$O$_5$ (Phosphorus Pentoxide): This is a highly acidic oxide. Phosphorus is a non-metal, and its oxides are strongly acidic.

The acidic character increases as we move from basic to acidic oxides in the periodic table. Therefore, the order of increasing acidic character is:

Na$_2$O $<$ MgO $<$ Al$_2$O$_3$ $<$ SiO$_2$ $<$ P$_2$O$_5$

Answer 2

Oxides can be arranged based on their acidic/basic nature across a period or down a group.
- Na$_2$O, MgO: Basic oxides (Group 1 and 2 metals)
- Al$_2$O$_3$: Amphoteric oxide
- SiO$_2$: Weakly acidic oxide
- P$_2$O$_5$: Strongly acidic oxide (non-metallic oxide)
Acidic character of oxides increases across a period (from left to right) due to increasing electronegativity and non-metallic character.
\[ \text{Na}_2\text{O}<\text{MgO}<\text{Al}_2\text{O}_3<\text{SiO}_2<\text{P}_2\text{O}_5 \] 
Answer: $\boxed{\text{A}}$