How does alternate freezing and thawing of water cause weathering to occur? freezing chemically alters the rock surfaces water expands when it freezes and cracks rocks open thawing causes rock particles to move from place to place

Weathering is a phenomenon in which rocks break down and the surface minerals are loosened up. This causes the rock to be transported away by the agents such as water, ice, and wind. 

The freezing or partial thawing of water trapped in the rocks will cause them to weather because given the proper temperature, they will freeze. Freezing of water causes it to expands, needing more volume to occupy and thus, breaking the rocks. From the given choices above, the best answer to this item is therefore the second choice. 

So3 that’s what i think

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged