Answer:
A log burning to ashes is a chemical change.
Explanation:
B. a physical combination of two or more different materials.
Answer:
pKb = 10.96
Explanation:
Tartaric acid is a dyprotic acid. It reacts to water like this:
H₂Tart + H₂O ⇄ H₃O⁺ + HTart⁻ Ka1
HTart⁻ + H₂O ⇄ H₃O⁺ + Tart⁻² Ka2
When we anaylse the base, we have
Tart⁻² + H₂O ⇄ OH⁻ + HTart⁻ Kb1
HTart⁻ + H₂O ⇄ OH⁻ + H₂Tart Kb2
Remember that Ka1 . Kb2 = Kw, plus pKa1 + pKb2 = 14
Kb2 = Kw / Ka1 → 1×10⁻¹⁴ / 9.20×10⁻⁴ = 1.08×10⁻¹¹
so pKb = - log Kb2 → - log 1.08×10⁻¹¹ = 10.96
Answer:
Below
Explanation:
Balanced form;

1.Benzene + Dioxygen = Carbon Dioxide + Water
2.Tricalcium phosphate +Carbon = Calcium phosphide + carbon monoxide
3.Nitrous acid react with oxygen to produce nitric acid.
4.This means that the carbon dioxide and limewater react to produce calcium carbonate and water.
5.Potassium react with bromine to produce potassium bromide
6. An aqueous solution of ferrous sulphate reacts with aqueous solution of sodium hydroxide to form a precipitate of ferrous hydroxide and sodium sulphate remains in the solution.