It is difficult to measure the enthalpy change of hydration accurately in a direct way because the hydration process can't be controlled directly. Instead, anhydrous and hydrated copper(II) sulfate can be dissolved in water. Each 'route' produces a solution of hydrated copper(II) sulfate.
The presence of an atmosphere, temperature, and distance from the Sun do not affect a planet's gravity. Are the objects in the solar system still or are they in motion? The Sun's gravity pulls the planets in orbit around it, and some planets pull moons in orbit around them.
B. Fossil
Why? Well skeleton seems like another answer BUT the definition of a fossil is an imprint of an organism on rock.
Example: A dinosaur presses it’s foot in dirt and it leaves a footprint or ‘fossil’ behind
To determine the equilibrium concentration of hydronium ions in the solution, we use the given value of the percent ionized. Percent ionized is the percent of the ions that is dissociated into the solution. It is equal to the concentration of an ionized species over the initial concentration of the compound multiplied by 100 percent. For this case, the dissociation of the weak acid has a 1 is to 1 ratio to the ionized species such that the concentration of the CH3COO- and H+ ions at equilibrium would be equal. We calculate as follows:
5.2% = 5.2 M H3O+ / 100 M CH3COOH
5.2 M H3O+ / 100 M CH3COOH = [H3O+] / 0.048 M CH3COOH
[H3O+] = 0.2496 M
