<h3>Explanation</h3>
Astatine has atomic number 85. "217" is the mass number of this isotope of At.
The mass number of an atom decreases by 4 as it undergoes alpha decay. Its atomic number decreases by 2. It emits an <em>alpha particle</em>, which is a helium-4 nucleus, in this process. The alpha particle has mass number 4 and atomic number 2.
The <em>daughter</em> nucleus has mass number 217 - 4 = 213 and atomic number 85 - 2 = 83. The atomic number of 83 corresponds to bismuth. Therefore the daughter nucleus is an atom of bismuth-213.
By convention, write the mass number A on the top-left corner of an element. Write its atomic number Z on the bottom-left corner. Note that A is always greater than Z for an isotope.
Answer:
Ka = 1.5 × 10⁻⁵
Explanation:
Butyric acid is a weak acid that ionizes according to the following equation:
CH₃-CH₂-CH₂-COOH(aq) ⇄ CH₃-CH₂-CH₂-COO⁻(aq) + H⁺(aq)
We can find the value of the acid dissociation constant (Ka) using the following expression:
where
[H⁺] is the molar concentration of H⁺
Ca is the initial molar concentration of the acid
We can find [H⁺] from the pH.
pH = -log [H⁺]
[H⁺] = antilog -pH = antilog -2.71 = 1.95 × 10⁻³ M
Then,
Your answer is <span>D) The angle of light from the sun as it reflects off the moon and viewed from the Earth's surface because of the way the sun hits the moon one side has to light the other doesn't and when the moon rotates the sun hits another part of the moon.
If you need more help I would be glad to help!
</span>*~"AB84"~*
This process is called meiosis! good luck!