<u>Answer:</u> The main group metal produce a basic solution in water and the reaction is 
<u>Explanation:</u>
Main group elements are the elements that are present in s-block and p-block.
The metals that are the main group elements are located in Group IA, Group II A and Group III A.
Oxides are formed when a metal or a non-metal reacts with oxygen molecule. There are two types of oxides which are formed: Acidic oxides and basic oxides.
- Acidic oxides are formed by the non-metals.
- Basic oxides are formed by the metals.
When a metal oxide is reacted with water, it leads to the formation of a base.
The general formula of the oxide formed by Group II-A metals is 'MO'
The chemical equation for the reaction of metal oxide of Group II-A and water follows:

Hence, the main group metal produce a basic solution in water and the reaction is 
It is a multiply question but your didn't include the choice in this question but the answer in this question is only so3 or s03 only. So3 is the only one that must exist as a set of resonance structures. So3 may be refer to a sulfur trioxide wich means a chemical compound of both trioxide and sulfur.
Answer: Wavelength associated with the fifth line is 397 nm
Explanation:

= Wavelength of radiation
E= energy
For fifth line in the H atom spectrum in the balmer series will be from n= 2 to n=7.
Using Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant =
= Higher energy level = 7
= Lower energy level = 2 (Balmer series)
Putting the values, in above equation, we get



Thus wavelength λ associated with the fifth line is 397 nm
Answer:
just read the explanation.
Explanation:
1.Maintaining a healthy, perennial plant cover.
2.Mulching.
3.Planting a cover crop – such as winter rye in vegetable gardens.
4.Placing crushed stone, wood chips, and other similar materials in heavily used areas where vegetation is hard to establish and maintain.
Hope this helps. :)