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SUBJECT CODE: 05

5. What is the molecular formula and IUPAC name of a saturated monocarboxylic acid having six carbon atoms?
A. [tex]C_5H_{11}COOH[/tex], heptanoic acid
B. [tex]C_6H_{13}COOH[/tex], heptanoic acid
C. [tex]C_5H_{11}COOH[/tex], hexanoic acid
D. [tex]C_6H_{13}COOH[/tex], hexanoic acid

6. Given the following structure:
What is the IUPAC name for the above structure?
A. Methyl ethanoate
B. Ethyl ethanoate
C. Propyl formate
D. Ethyl acetate

7. During summer, the average value for the temperature measured in a certain chemistry laboratory is 298.15 K. How many decimal places are there in the measured value?
A. 5
B. 3
C. 2
D. 1

8. Which of the following is the CORRECT Lewis electron-dot symbol of [tex]MgO[/tex]? (Atomic number: [tex]Mg = 12[/tex] and [tex]O = 8[/tex])
A. [tex]Mg^{+}: \ddot{O}^{2-}[/tex]
B. [tex]Mg^{+2}: \ddot{O}[/tex]
C. [tex]Mg^{+}: \ddot{O}_{:}[/tex]
D. [tex]Mg^{+2}: \ddot{O}^{2-}[/tex]



Answer :

GinnyAnswer
Let's go through the multiple-choice questions step-by-step and ensure we find the correct answers.

### 1. Molecular Formula and IUPAC Name of a Saturated Monocarboxylic Acid with Six Carbon Atoms

A saturated monocarboxylic acid means that the molecule contains only single bonds (saturated) and one carboxylic acid group (-COOH). The main chain of this acid must have six carbon atoms.

For an acid with six carbons in the main chain, the formula should be [tex]\(C_6H_{12}COOH\)[/tex] (the correct molecular formula being C7H14O2). Hexanoic acid is the correct name for a six-carbon acid with no double bonds.

Answer: D. [tex]$C_6H_{13}COOH$[/tex], hexanoic acid

### 2. IUPAC Name for a Given Structure

This question seems to be missing the structure for analysis. However, given the choices and common knowledge:
- Methyl ethanoate is an ester formed from methanol and ethanoic acid.
- Ethyl ethanoate (Ethyl acetate) is an ester formed from ethanol and ethanoic acid.
- Propyl formate is an ester formed from propanol and formic acid.
- Ethyl acetate is a common name for ethyl ethanoate.

Assuming the question hinted towards a common ester, the correct answer would likely be:

Answer: D. Ethyl acetate

### 3. Number of Decimal Places in the Measured Value (298.15 K)

The number of decimal places refers to the digits following the decimal point. In 298.15, there are two digits after the decimal.

Answer: C. 2

### 4. Correct Lewis Electron-Dot Symbol of MgO

Magnesium (Mg) has an atomic number of 12, meaning it has 2 electrons in its outer shell. Oxygen (O) has an atomic number of 8, with 6 electrons in its outer shell.

Mg will lose 2 electrons to form [tex]\(Mg^{2+}\)[/tex], and O will gain 2 electrons to form [tex]\(O^{2-}\)[/tex], resulting in the electron-dot structure:
[tex]\[ \text{Mg}^{2+}: \cdots \text{O}^{2-} \cdots \][/tex]

Answer: B. Mg^{2+}: \cdots \text{O}

### Summary of Answers:

1. D. C_6H_{13}COOH, hexanoic acid
2. D. Ethyl acetate
3. C. 2
4. B. Mg^{2+}: \cdots \text{O}

I hope these explanations help you understand the concepts better! If you have more questions, feel free to ask.

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