Zn(s) + HCl(aq)→ ZnCl (aq) +H2 (g) the combination that will affect the rate of reaction is
Temperature, concentration and surface area (answer A)
If Zn(s) is broken into powder the surface area increases leading to speeding up the rate of reaction. When the concentration of the of dissolved reactant is increased the rate of reaction increases. An increase in temperature led to increase in movement of particle and more collision happen hence the rate of reaction is increased.
We are asked to provide the net ionic equation for the reaction of HF (aq) and NaF (aq). HF is a weak acid and is in the following equilibrium:
HF (aq) ⇄ H⁺ (aq) + F⁻ (aq)
Meanwhile, NaF (aq) is an ionic compound that will dissociate completely in aqueous solutions:
NaF (aq) → Na⁺ (aq) + F⁻ (aq)
We can combine the ionic species with HF, as we are told to show F⁻ as a reactant:
HF (aq) + Na⁺ (aq) + F⁻ (aq) → HF (aq) + Na⁺ (aq) + F⁻ (aq)
We can eliminate the spectator ions, which in this case are Na⁺ ions, and this leaves us with the net ionic equation involving F⁻:
HF (aq) + F⁻ (aq) → HF (aq) + F⁻ (aq)
In this instance, the proton is just transferred between F⁻ ions and the end result is the formation of more HF, so there is no net reaction taking place.