Answer: <u>Four</u>Explanation: Calcium Sulfide is an ionic compound made up of Ca²⁺ and S²⁻.
Ca²⁺ is formed as,
Ca → Ca²⁺ + 2 e⁻
These two electrons are accepte by Sulfur as,
S + 2 e⁻ → S²⁻
So, before accepting 2 electrons S was having six valence electrons, after accepting two electrons from Ca it has 8 electrons which are present in four pairs as shown below,
It became the model for the Chicago income and property tax program. He used this plan to avoid prosecution for the Chicago fire. This contest-winning design opened Chicago streets to new forms of transportation.
The orbits of the Halley-type comets suggest that they were originally long-period comets whose orbits were perturbed by the gravity of the gas giants and directed into the inner Solar System.
Answer:
Explanation:
Heat flow equation => q = m·c·ΔT
m = mass in grams = 10.00 grams
c = specific heat (a constant) = 0.900j/g·°C
ΔT = temperature change in °C = 50°C - 25°C = 25°C
q = (10.00g)(0.900j/g·°C)(25°C) = 225 joules absorbed*
*absorbed => endothermic process => need to show 'plus' energy change.
If the reactions were an exothermic process the problem would use terms like energy released, energy lost, energy given-up, etc... => would require using a 'negative' signage before the calculated energy value. So, the correct choice is the +225 joules value.