P and S
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<span>Hydroelectric energy uses the movement of water to spin a turbine and produce electricity. Coal is a fossil fuel that is burned as an energy source, which results in emissions such as carbon dioxide, nitrogen, and sulfur. Coal use is associated with waste products both from the mining process to acquire the coal and also from the actual use of coal itself. Hydroelectric energy does not involve waste, but does pose potential problems to waterways. Coal use is more common than the use of hydroelectric energy.</span>
A student fires a bow and arrow in gym class and all his arrows land close to eachother but not on the bullseye. this student could be said to be:
precise but not accurate
The water well begin to freeze and turn into soild. why? because the temperature of the the freezer is getting the water bottle cold so when that cold temperature hits that that bottle which has liquid in it so you should know that when liquid is into cold air it well so be soild so when you put the water bottle in the freezer it will be soild.
and also remember gas - liquid - soild gas change to liquid by hot air and liuid change to soild by clod air
hoped i helped
Answer:
1)Na2O
let the valency of Na is x
2(x)+(2)=0
2x+2=0
2x=-2
x=-1
2)ZnO
let the valency of Zn is x
x+2=0
x=-2
3)Al2O3
let the valency of Al is x
2(x)+3(2)=0
2x+6=0
2x=-6
x=-3
4)MgO
let the valency of Mg is x
x+2=0
x=-2
