Answer: HA + H2O ⇌ H3O+ + H- (option #4)
Explanation: Since the acid is weak you have to use a ⇌ (equilibrium) sign. Equilibrium is denoted in a chemical equation by the ⇌ symbol. Also, when any acid dissolves into water, it produces hydronium (H3O+ or H+). Therefore, the fourth chemical reaction is your answer.
It is a Compound. have a nice day
The enthalpy change of the reaction when sodium hydroxide and sulfuric acid react can be calculated using the mass of solution, temperature change, and specific heat of water.
The balanced chemical equation for the reaction can be represented as,

Given volume of the solution = 101.2 mL + 50.6 mL = 151.8 mL
Heat of the reaction, q =
Δ
m is mass of the solution = 151.8 mL * 
C is the specific heat of solution = 4.18 
ΔT is the temperature change = 
q = 
Moles of NaOH =
NaOH
Moles of
= 
Enthalpy of the reaction = 
Answer:
The strength of a bond between two atoms increases as the number of electron pairs in the bond increases.
Explanation: