Calculate the enthalpy for this reaction: 2C(s) + H2() → C2H2(g)
ΔH° = ??? kJ

Given the following thermochemical equations:
C2H2(g) + (5/2)O2(g) → 2CO2(g) + H2O(ℓ)
ΔH° = -1299.5 kJ

C(s) + O2(g) → CO2(g)
ΔH° = -393.5 kJ

H2(g) + (1/2)O2(g) → H2O(ℓ)
ΔH° = -285.8 kJ

Which statement correctly identifies the scientific question and describes why the question is scientific? question 1 refers to the supernatural.question 2 reflects a moral or social value.question 3 refers to something that can be measured.question 4 reflects a question that can’t be observed.

Imagine that a new planet is discovered with two moons of equal mass: moon a and moon b. the mass of the new planet is greater than the combined mass of its moons. moon a is farther away from the new planet than moon b. what is the planet's gravitational pull on moon a compared to the planet's gravitational pull on moon b? the planet's gravity repels moon a with a greater force than it repels moon b, which is why moon a is farther away. the gravitational pull on moon b is greater than on moon a because moon b is closer to the new planet than moon a. the gravitational pull on moon b is greater than on moon a because moon b is farther away from the new planet than moon a. the gravitational pull on moon a is the same as the gravitational pull on moon b because distance does not affect the planet's gravity.

Suppose that some of the compound spilled out of the crucible after it was heated. would that cause the percent by mass of water in the compound determined by the experiment to be too low, too high, or unchanged? briefly explain your answer.