Answer:
Flood barriers
Explanation:
Many towns in flood-prone areas are surrounded by flood barriers that are built to hold back rising water during seasonal highs.
- Flood barriers are water resistant walls that are used to prevent breaking water during a high period of inundation from their channels.
- They are usually vertical artificial structures which can be temporary or permanent.
- They help to hold or contain the flood water during the high season.
- These walls prevents flood plains and other nearby areas from getting flooded during the rainy season.

The element having valency of 1 is ~
Missing question:
1) the rate of dissolving reaches zero
<span>2) the rate of crystallization reaches zero </span>
3) the rate of dissolving is zero and the rate of crystallization is greater than zero.
<span>4) both the rate of dissolving and the rate of crystallization are equal and greater than zero.
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Answer is: 4) both the rate of dissolving and the rate of crystallization are equal and greater than zero.
Silver chloride (AgCl) dissolves and form silver and chlorine ions, in the same time silver and chlorine ions crystallizate and form solid salt silver chloride.
In equilibrium rates of dissolvinf and crysallization and concentration of ions do not change.
When sulfur dioxide combines with water and air, it forms sulfuric acid, which is the main component of acid rain. Acid rain can: cause deforestation. acidify waterways to the detriment of aquatic life