SiO2 + 4HF → SiFe + 2H2O
write 5 possible mole ratios

Here's what I get

Explanation:

SiO₂ + 4HF ⟶ SiF₄ + 2H₂O  

The molar ratios are the same as the coefficients in the balanced equation.

Some of the molar ratios are

 SiO₂:HF = 1:4

SiO₂:SiF₄ = 1:1

SiO₂:H₂O = 1:2

  HF:SiF₄ = 4:1

  HF:H₂O = 4:2

 SiF₄:H₂O = 1:2

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.