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C₅H₅ + Fe → Fe(C₅H₅)₂
Put a coefficient of 2 in front of C₅H₅ on the left side because there is a subscript of 2 after C₅H₅ in parenthesis on the right.
2C₅H₅ + Fe → Fe(C₅H₅)₂
Fe (iron) is already balanced since there is one on each side, so we don't need to change anything for that.
This is a synthesis reaction because two reactants, C₅H₅ and Fe, are yielding a single product, Fe(C₅H₅)₂.
Hope this helps!
Answer:
Some metals can be extracted from compounds by heating with carbon atom because they are less reactive than carbon and some metals cannot be extracted because they are more reactive than carbon atom.
Explanation: If the metal is less reactive than carbon atom so the carbon atoms make bond with oxide or other atom present with metal and the metal is free from that oxide or that element. But if the reactivity of metal is higher than carbon is unable to remove the oxide or element.
Answer: The molar mass of each gas
Explanation:
Mole fraction is the ratio of moles of that component to the total moles of solution. Moles of solute is the ratio of given mass to the molar mass.

Suppose if there are three gases A, B and C.
a) 
b) 
c) 
moles of solute =
Thus if mass of each gas is known , we must know the molar mass of each gas to know the moles of each gas.
2H₂₍g₎ + O₂ ₍g₎→ 2H₂O
138 mol H₂ × (2 mol H₂O ÷ 2 mol H₂)= 138 mol H₂O
64 mol O₂ × (2 mol H₂O ÷ 1 mol O₂)= 128 mol H₂O
128 mol H₂O