From the balanced equation: 
<span>1mol C3H8 requires 5mol O2 for combustion </span>
<span>Molar mass C3H8 = 44g/mol </span>
<span>8.8g C3H8 = 8.8/44 = 0.2mol C3H8 </span>
<span>This will require 5*0.2 = 1.0mol O2 </span>
<span>Molar mass O2 = 32g/mol </span>
<span>Therefore 32g of O2 required.
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Ionic crystals are hard because of tight packing lattices, say, the positive and negative ions are strongly attached among themselves.
        
             
        
        
        
Fuel......................................
        
             
        
        
        
Answer:
S²⁻(aq) + Cr²⁺(aq) ⇄ CrS(s)
Explanation:
The molecular equation includes all the species in the molecular form. Usually, it is useful to write this first to balance the equation. This is a double displacement reaction.
K₂S(aq) + Cr(NO₃)₂(aq) ⇄ 2 KNO₃(aq) + CrS(s)
The full ionic equation includes all ions and the species that no dot dissociate in water.
2 K⁺(aq) + S²⁻(aq) + Cr²⁺(aq) + 2 NO₃⁻(aq) ⇄ 2 K⁺(aq) + 2 NO₃⁻(aq) + CrS(s)
The net ionic equation includes only those ions that participate in the reaction and the species that do not dissociate in water.
S²⁻(aq) + Cr²⁺(aq) ⇄ CrS(s)