What kind of change causes iron to rust

it would be oxidation

Explanation:

when water combines with air and has contact with iron. it rusts over a short period of time. there fore Oxdiation.

Moisture around the iron's surroundings can cause the iron to rust

Explanation:

Rust is the oxidized form of iron. Iron rusts because it combines with oxygen. The oxygen needs moisture as a catalyst and reactant to accelerate the reaction, so in the absence of moisture, iron won't rust. So the thing that causes iron to rust is the presence of water or moisture from which the iron can take the oxygen it wants

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.

answer: grassland biomes are closer to the equator and receive more rain.

grasslands are biomes that are dominated by grasses rather shrubs and trees. savanna are biomes that exhibit grasses, shrubs and small tree as vegetation. grasslands are located near the equator of the earth. these are found in north america. savanna biomes are found in africa, south america, australia and india. grassland exhibit moderate climatic conditions, it receives   amount of rainfall higher than savanna.   therefore, savanna exhibit dry and hot climatic conditions.