Finely ground nickel(ii) hydroxide is placed in a beaker of water. it sinks to the bottom of the beaker and remains unchanged. an aqueous solution of hydrochloric acid (hcl) is then added to the beaker, and the ni(oh ) 2 disappears. which equation best describes what occurred in the beaker? a. ni(oh ) 2 (s) + hcl(aq) → nio(aq) + h 2(g) + hcl(aq) b. ni(oh ) 2 (s) + 2hcl(aq) → nic l 2 (aq) + 2 h 2 o(l) c. ni(oh ) 2 (s) + 2 h 2 o(l) → nic l 2 (aq) + 2 h 2 o(l) d. ni(oh ) 2 (s) + 2 h 2 o(l) → nicl 2(aq) + 3h 2o(l) + o 2(g)

9. write the chemical equation for the following word equations. include symbols for physical states in the equation. a. solid zinc sulfide + oxygen gas -> solid zinc oxide + sulfur dioxide gas b. aqueous hydrochloric acid + aqueous barium hydroxide -> aqueous barium chloride + water

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.

Consider the heating curve of h2o and line segments a, b, and c. several changes are taking place at a, b, and c. all but one would be an appropriate description as e move through segments a, b and then c.