I think it will be B. Hope it helps :)
<h3>
Answer: Si (choice D)</h3>
This is the element Silicon.
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Explanation:
First convert each percentage to its decimal form.
For example, 92.2297% converts to 0.922297 after moving the decimal point two spots to the left.
After doing that, multiply those decimal values with their respective atomic mass unit (amu) values.
- 27.9769 * 0.922297 = 25.8030109393
- 28.9765 * 0.046832 = 1.357027448
- 29.9738 * 0.030872 = 0.9253511536
Then we add up the results
25.8030109393 + 1.357027448 + 0.9253511536 = 28.0853895409
That rounds to about 28.085
Then look at the periodic table to see the atomic mass of Cobalt (Co), Aluminum (Al), Nickel (Ni) and Silicon (Si). The mass values listed in the periodic table are weighted averages of all the isotopes. The units for the mass are still in amu.
- Cobalt = 58.933
- Aluminum = 26.982
- Nickel = 58.693
- Silicon = 28.085
We have a match with silicon, showing that <u>choice D</u> is the final answer.
Answer:
c) more OH⁻ ions than H₃O⁺ ions
Explanation:
A substance with a PH of 9 implies that it has more OH⁻ ions than H₃O⁺ ions.
Such substances are said to be an alkaline or a base.
A base is a substance the produces excess hydroxyl ion in aqueous solutions.
An acid will produce excess hydroxonium ions in a solution.
So, the pH scale is used to indicate whether a substance is an acid or base or non of them.
Acids have pH of less than 7
Bases have pH of > 7
