B because....................
The average weight of an atom of an element, formerly based on the
weight of one hydrogen atom taken as a unit or on 1/16 (0.0625) the
weight of an oxygen atom, but after 1961 based on 1/12 the weight of the
carbon-12 atom.
The two elements that have the same properties as sodium are potassium and rubidium .
<h3>What is periodic table?</h3>
The periodic table is an arrangement of the elements in order of increasing atomic number.
From the list, the two elements that have the same properties as sodium are potassium and rubidium .
Proton has an atomic number of 20 and a mass number of 40. The number of electrons is the same as the number of protons. Given that the atomic number is the number of protons present, we have 20 electrons and 20 protons.
Number of neutrons = Mass number - Number of protons
= 40 - 20 = 20 neutrons
Learn more about periodic table:brainly.com/question/11155928
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Answer:
The answer is "2%"
Explanation:
Equation:
Formula:
![Ka = \frac{[H^{+}][NO_2^{-}]}{[HNO_2]}](https://tex.z-dn.net/?f=Ka%20%3D%20%5Cfrac%7B%5BH%5E%7B%2B%7D%5D%5BNO_2%5E%7B-%7D%5D%7D%7B%5BHNO_2%5D%7D)
Let
![[H^{+}] = [NO_2^{-}] = x](https://tex.z-dn.net/?f=%5BH%5E%7B%2B%7D%5D%20%3D%20%5BNO_2%5E%7B-%7D%5D%20%3D%20x)
at equilibrium
therefore,
![[H^{+}] = 2.0\times 10^{-2} \ M = 0.02 \ M](https://tex.z-dn.net/?f=%5BH%5E%7B%2B%7D%5D%20%3D%202.0%5Ctimes%2010%5E%7B-2%7D%20%5C%20M%20%3D%200.02%20%5C%20M)
Calculating the % ionization:
![= \frac{([H^{+}]}{[HNO_2])} \times 100 \\\\= \frac{0.02}{1}\times 100 \\\\= 2\%\\\\](https://tex.z-dn.net/?f=%3D%20%5Cfrac%7B%28%5BH%5E%7B%2B%7D%5D%7D%7B%5BHNO_2%5D%29%7D%20%5Ctimes%20100%20%5C%5C%5C%5C%3D%20%5Cfrac%7B0.02%7D%7B1%7D%5Ctimes%20100%20%5C%5C%5C%5C%3D%202%5C%25%5C%5C%5C%5C)
patterns are important because they prove life has meaning ( or if you mean
Scientifically is is that the ability to recognize and create patterns help scientists make predictions based on there observations.
