4. Data: Substance H2O(l) CO2(g) Ethane, C2H6(g) Ethene, C2H4(g) DHfq/kJ mol-1 –285.5 –393 –83.6 +52.6 (a) Write equation for the complete combustion of: (i) ethane (ii) ethene (iii) hydrogen (b) Calculate the enthalpy of combustion in each case. (c) From the results obtained in (b), calculate the enthalpy change for the reaction: C2H4(g) + H2(g) ® C2H6(g)

Darla claims that the first periodic table developed by mendeleev was not completely accurate, so it is not useful at all. harmony argues that it establish the periodic table we use today, making it more credible. who is correct and why? darla is correct, because a model that has any mistakes should be thrown out. darla is correct, because a good model would not need to change. harmony is correct, because mendeleev’s model had all of the information correct in the first version. harmony is correct, because mendeleev’s model made predictions that came true.

(1.6 × 10-19)(5.0 × 106) = c × 10d identify the missing numbers below to show the result of multiplying the numbers.

Which set of characteristics best describes igneous rock? a) largest type of rock, made of organic matter, hardest type of rock b) least abundant type of rock, made of other rocks, made mostly of minerals c) found on all continents, contains wavy bands of stripes, contains fossils d) most abundant type in earth's crust, made of magma/lava, contains no fossils