2g mass of magnesium are reacted with excess dilute acid according to the equation Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g)
(Relative atomic mass of Mg=24, molar volume at rtp= 24dm³)
The volume of hydrogen, measured at rtp, that is produced is
(A) 1000cm³
(B) 1500cm³
(C) 2000cm³
(D) 24000cm³

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.