Answer:
Explanation:
Let A₀ = the original amount of ⁵⁵Co
.
The amount remaining after one half-life is ½A₀.
After two half-lives, the amount remaining is ½ ×½A₀ = (½)²A₀.
After three half-lives, the amount remaining is ½ ×(½)²A₀ = (½)³A₀.
The general formula for the amount remaining is:
A =A₀(½)ⁿ
where n is the number of half-lives
n = t/t_½
Data:
A = 1.90 ng
t = 45 h
t_½ = 18.0 h
Calculation:
(a) Calculate n
n = 45/18.0 = 2.5
(b) Calculate A
1.90 = A₀ × (½)^2.5
1.90 = A₀ × 0.178
A₀ = 1.90/0.178 = 10.7 ng
The original mass of ⁵⁵Co was .
1. Answer is d. all of the above.
Climate can be defined as the data collection of weather conditions of a long period of time in a certain area. The weather conditions that affect to the climate are temperature, precipitation, atmospheric pressure, wind and so on. Any changes in weather can change the global climate.
2. Answer is c. ozone.
Trees release oxygen and water vapor into the atmosphere but not ozone. The oxygen gas is released by trees as the by-product of photosynthesis. This is the natural way of production of oxygen gas. Water vapor can be released due to the transpiration of trees.
Answer:
1,869.97 grams of Be(NO3)2
Explanation:
Be(NO3)2 = Be N2 O6
Be=9.012182g/mole
N2=28.0134g/mole
O6=96g/mole
therefore Be(NO3)2 gives you 187.56g in one mole
so 9.97 moles means there is 9.97 times more
9.97mole Be(NO3)2 * 187.56g Be(NO3)2/1mole Be(NO3)2 = 1,869.97g of Be(NO3)2
Because each color is refracted differently, each bends at a different angle, resulting in a fanning out and separation of white light into the colors of the spectrum. Water droplets in the air can act in a manner similar to that of a prism, separating the colors of sunlight to produce a spectrum known as a rainbow.
Answer is: 55.125 grams <span>of propane must be burned.
</span>Balanced chemical reaction: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.
Make proportion: 1 mol(C₃H₈) : 2220 kJ = n(C₃H₈) : 2775kJ.
n(C₃H₈) = 2775 kJ·mol ÷ 2220 kJ.
n(C₃H₈) = 1.25 mol.
m(C₃H₈) = n(C₃H₈) · M(C₃H₈).
m(C₃H₈) = 1.25 mol · 44.1 g/mol.
m(C₃H₈) = 55.125 g.
n - amount of substance.
