Explanation:
postive:
-flood control- the flood storage capacity of three gorges dam reservoir is 22 cubic meters and this capacity can reduce the frequency of major downstream flooding from once every ten years to once every 100 years
negative:
-water pollution- along with the river flowing there is a large number of land experiencing erosion which lead to tons of sands and pepples into he Yangtze river and stay at the upstream and makes great water pollution about Yangtze river
when price meets marginal cost
Overall transformation : Ar-H to Ar-R
Named after Friedel and Crafts who discovered the reaction in 1877.
Reagent : normally the alkyl halide (e.g. R-Br or R-Cl) with aluminum trichloride, AlCl3, a Lewis acid catalyst.
The AlCl3 enhances the electrophilicity of the alkyl halide by complexing with the halide.
Electrophilic species : the carbocation (i.e. R +) formed by the "removal" of the halide by the Lewis acid catalyst
The reactive electrophile, the carbocation is prone to rearrangement to a more stable carbocation which will then undergo the alkylation reaction.

Friedel-Crafts reactions are limited to arenes as or more reactive than mono-halobenzenes
Other Lewis acids such as BF3, FeCl3 or ZnCl2 can also be used
Other sources of carbocations can also be used:
from loss of water from alcohols treated with acid such as H2SO4
from the protonation of alkenes by acid such as H2SO4
Alkylation products can also be obtained by the reduction of Friedel-Crafts acylation products
Explanation:
If heat is released in a reaction, enthalpy Change in the reaction is negative, then it will be exothermic
Answer:
just put down five explorers that you know
Explanation:
the rest is easy. your just overthinking it
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