Answer:
70%of 2000 = 1400
2000 tonnes of hematite contains 1400 tonnes iron oxide .
1400 tonnes of fe2O3
fe2O3 have molar mass 159.69
calculate moles = given mass/molar mass
moles = 1400000000/159.69
moles = 8766986
one mole contains = 112 g of fe
so 8766986 moles will contain = 112×8766986
= 981,902,432 grams of ferrous
which is nothing but equal to 981.90 tonnes of iron!!
Your first step should be to analyse the compound. For example, if the compound is carbon, you know it always has a valence of four, so, if it has a formula C2H4 (ethylene) it obviously has a double bond. There are difficulties here because benzene C6H6 can be considered to have 6 1.5 C-C bonds, being aromatic.
A second step is to look at its structure. Double bonds are traditionally shorter than single bonds; triple bonds shorter still. Covalent bonds do have typical lengths, nevertheless you can still have problems.
<span>A third step is to consider reactivity. For example, if you have a C=C double bond, you can add, say, bromine to it Thus C2H4 gives C2H4Br2, and by adding two bromine atoms you know you have one double bond. Again, benzene becomes an awkward molecule, but because of this, you know benzene does not have double bonds in the traditional sense</span>
