Answer : Normally in any chemical reaction, if the enthalpy change i.e. ΔH is positive which means it is greater than zero then it can be called as an Endothermic Reaction.
Whereas, the system under study is absorbing heat that is produced during the reaction. So if ΔH is found to be positive then it can be called as endothermic reaction.
Solids have a definite shape, and a definite volume.
Liquids have a definite volume, but have no definite shape.
Gas have neither a definite volume nor a definite shape.
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The two main types of weathering are material and chemical.
Mechanical weathering is the disintegration of rock into smaller and smaller fragments.
Chemical weathering transforms the original material into a substance with a different composition and different physical characteristics.
<span>When an electron, which is negatively charged, moves towards an electronegative atom, the electronegative atom pulls in the electron. This causes the electronegative atom to be reduced. This entire process also releases energy.</span>
Just look it up on goog^le or a chart