An element with atomic no. __________ will form an acidic oxide

To determine which element will form an acidic oxide, we need to consider the periodic table.

1. Look for the element with the given atomic number.
2. Identify the group or family of that element.
3. Determine the general trend for oxide formation within that group.

In general, nonmetals tend to form acidic oxides, while metals tend to form basic or amphoteric oxides.

So, if the element with the given atomic number is a nonmetal, it is likely to form an acidic oxide. However, if it is a metal, it is less likely to form an acidic oxide.

Please provide the specific atomic number so that we can determine the element and its oxide formation characteristics.