If the grade of the ore is 37.3% nickel, then the unknown quantity to get 10 grams of nickel is 0.373 x = 10 grams or x = 10/0.373=26.8 grams or 0.0268 kg needed to dig up to recover the 10 grams of nickel. At this grade of ore, 1 kilogram would yield 373 grams of nickel.
When the reactant is single compound before the reaction and become more than single compound after reaction is called decomposition reaction
Sedimentary rocks don't necessarily make fossils. Although when animals die on top of the rocks and are never moved, blown away, etc they can get trapped under the growing rock. Which is why fossils are often found in sedimentary rocks.
Answer:
5)0.53liters
6)1.634.6°c
Explanation:

5) v1=25liters, t1=12000°c. v2=?, t2=250°c
v2=(250×25)/12000
v2=6250/12000
v2=0.52liters
6)v1=130,v2=85, t1=2500, t2=?
t2=(85×2500)/130
t2=212500/130
t2= 1634.6°c