Taking into account the scientific notation, the result of the subtraction is -4.20689×10⁻².
<h3>Scientific notation</h3>
Scientific notation is a quick way to represent a number using powers of base ten, where the numbers are written as a product:
a×10ⁿ
where:
- a is a real number greater than or equal to 1 and less than 10, to which a decimal point is added after the first digit if it is a non-integer number.
- n is an integer, which is called an exponent or an order of magnitude. Represents the number of times the comma is shifted. It is always an integer, positive if it is shifted to the left, negative if it is shifted to the right.
<h3>Subtraction in scientific notation</h3>
When the numbers to be added do not have the same base 10 exponent, the base 10 power with the highest exponent must be found. In this case, the highest exponent is -2.
Then all the values are expressed as a function of the base 10 exponent with the highest exponent. In this case: 3.11×10⁻⁵= 0.00311×10⁻²
Taking the quantities to the same exponent, all you have to do is subtract what was previously called the number "a". In this case:
0.00311×10⁻² - 4.21×10⁻²= (0.00311 - 4.21)×10⁻²= -4.20689×10⁻²
Finally, the result of the subtraction is -4.20689×10⁻².
Learn more about operations in scientific notation:
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Answer: Carbon
Explanation: Organic compounds are those made by carbon atoms that link to other carbon or elements such as nitrogen, hydrogen or oxygen with covalent bonds.
The presence of these compounds were associated with living things, because most of them are produced by plants or animals. However nowdays substances like polymers and other synthetically made molecules can also be considered as organic since they are made of carbon.
They are substitution reactions
hope that helps
Answer:
Option D.
Explanation:
First we convert the given reactant masses into moles, using their respective molar masses:
- 4.00 g H₂ ÷ 2 g/mol = 2 mol H₂
- 6.20 g P₄ ÷ 124 g/mol = 0.05 mol P₄
0.05 moles of P₄ would react completely with (6*0.05) 0.3 moles of H₂. There are more H₂ moles than required, meaning H₂ is in excess and P₄ is the limiting reactant.
Now we<u> calculate how many PH₃ moles could be formed</u>, using the <em>number of moles of the limiting reactant</em>:
- 0.05 mol P₄ *
= 0.2 mol PH₃
Finally we <u>convert 0.2 mol PH₃ into grams</u>, using its <em>molar mass</em>:
- 0.2 mol PH₃ * 34 g/mol = 6.8 g
So the correct answer is option D.
The different types of microscopes are all necessary because not all experiments require the same level of magnification. For dissections low magnification is sufficient, so a dissecting microscope works very well, while for viewing single cells the 1000 fold magnification of a compound light microscope is more accurate.
