Answer:
75603.86473 K
Explanation:
Given that:
The 1st excited electronic energy level of He atom = 3.13 × 10⁻¹⁸ J
The objective of this question is to estimate the temperature at which the ratio of the population will be 5.0 between the first excited state to the ground state.
The formula for estimating the ratio of population in 1st excited state to the ground state can be computed as:

From the above equation:
Δ E = energy difference = 3.13 × 10⁻¹⁸ J
k = Boltzmann constant = 1.38 × 10⁻²³ J/K

Thus:





T = 75603.86473 K
Acids are ionic compounds that break apart in water to form a hydrogen ion. The strength of an acid is based on the concentration of hydrogen ions in a solution. The more hydrogen ions, the stronger the acid. Bases are ionic compounds that break apart in water to form negatively charged hydroxide ions. The strength of the base is based on the concentration of hydroxide ions.
Hence, letter C is the correct answer.
The concentration may be expressed as % m/m, this is the mass of ions in 100 mass units of solution, whose formula is:
% m/m = [mass of ions / mass of solution]*100
Then,
%m/m = [8.5*10^ -3 grams of calcium ions] / [490 grams of solution] * 100 =
% m/m = 1.74 * 10^ -5 %
Answer: 1.74 * 10 ^ -5 %
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