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# Tutor profile: Flora U.

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Flora U.
Student at University of California, Irvine
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## Questions

### Subject:Basic Chemistry

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Question:

What are the number of protons, neutrons, and electrons in the ion below ? N^+

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Flora U.

First of all, know what an ion is. An ion is an atom with a net charge caused by the loss or gain of electrons . In this problem, N(nitrogen) has a positive charge. Since electrons have a negative charge, a net positive charge on nitrogen means there was a loss of an electron that caused nitrogen to become more positive. The number of protons in an element is always the atomic number found on the periodic table. Protons: 7 The number of electrons is normally the same as the number of protons. However, in an ion like N^+, there was a loss of an electron that caused the positive charge. Therefore, we will subtract the number of protons by 1 to show the loss of an electron. Electrons: 7 - 1 = 6 The number of neutrons can be known by this formula: (number of protons) + (number of neutrons) = (atomic mass of the element) We already know that the number of protons was 7 and the atomic mass can be found on the periodic table. Based on the periodic table, the atomic mass of Nitrogen is 14. 7 + (number of neutrons) = 14 14 - 7 = (number of neutrons) (number of neutrons) =7

### Subject:Biology

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Question:

Explain why membrane fluidity increases in unsaturated fatty acids rather than in saturated fatty acids.

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Flora U.

Unsaturated fatty acids have kinks caused by double bonds in their tails. The kinks make it difficult for them to stack closely and stay packed together. Therefore, the kinks that prevent tight packing allow molecules to get through them easily. In saturated fatty acids they have no kinks in their tails and can easily pack together leaving almost no room for molecules to get through.

### Subject:Algebra

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Question:

Solve the following two equations using the Order of Operations. Why are the two solutions different? 18 - ( 3 - 12 ÷ 4) 18 - 3 - 12 ÷ 4

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Flora U.

18 - ( 3 - 12 ÷ 4) = 18 18 - 3 - 12 ÷ 4 = 12 Although these two equations look similar, the answers are different because of the Order of Operations. Recall PEMDAS which stands for Parentheses, Exponent, Multiplication, Division, Addition, Subtraction. The acronym, PEMDAS, tells you the order in which you should solve first. In the first equation, we need to solve the expression in the parentheses first. (3 - 12 ÷ 4) There is a division and a subtraction sign in the parentheses. According to PEMDAS, division comes before subtraction (3 - 3) = 0 Now that we know the expression in the parentheses equals 0, we can solve the equation as normal 18 - 0 =` 18 In the second equation, there are subtraction and division signs. PEMDAS states to do division before subtraction 18 - 3 - 3 Now that we are only left with subtraction signs, we can solve the equation as normal. 18 - 3 - 3 = 12

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