This would be C. A car rusting
Answer:

Explanation:
To solve this problem, we can use the Combined Gas Laws:

Data:
p₁ = 1.7 kPa; V₁ = 7.5 m³; T₁ = -10 °C
p₂ = ?; V₂ = 3.8 m³; T₂ = 200 K
Calculations:
(a) Convert temperature to kelvins
T₁ = (-10 + 273.15) K = 263.15 K
(b) Calculate the pressure

The formula for K+ and S-2 is K2S because you need 2 potassium ions to balance out the sulfide ion
Answer: 40.1%
Explanation: The mass of calcium in this compound is equal to 40.1 grams because there's one atom of calcium present and calcium has an atomic mass of 40.1 . The molar mass of the compound is 100.1 grams. Using the handy equation above, we get: Mass percent = 40.1 g Ca⁄100.1 g CaCO3 × 100% = 40.1% Ca.
Answer:
The answer is B. Atomic Mass