Question 1

Which of the following best describes the difference between a saturated and an unsaturated hydrocarbon?

Accepted Answer

Saturated hydrocarbons contain only single bonds between carbon atoms, while unsaturated hydrocarbons contain at least one double or triple bond.

Question 2

What is the correct IUPAC name for the following structure?

(CH₃)₂CHCH₂CH₃

Accepted Answer

2-methylbutane

Question 3

Which of the following molecules is capable of existing as isomers?

A. Ethane
B. Propane
C. Butane
D. Methane

Accepted Answer

Butane

Question 4

Given the condensed structure CH₃CH₂C≡CCH(CH₃)₂, what is the correct IUPAC name?

Accepted Answer

4,4-dimethyl-2-hexyne

Question 5

Which quantum number defines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 6

How many unpaired electrons are present in a nitrogen atom in its ground state?

Accepted Answer

3

Question 7

Which of the following electron configurations violates Hund’s Rule?

Accepted Answer

1s² 2s² 2p² (with both electrons paired in the same 2p orbital)

Question 8

What is the complete electron configuration for sulfur (atomic number 16)?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^4$$

Question 9

Which set of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2}$$

Question 10

Which of the following best explains why the 4s orbital fills before the 3d orbital in multi-electron atoms?

Accepted Answer

The 4s orbital is lower in energy than the 3d orbital due to electron shielding and penetration effects.

Question 11

What is the condensed electron configuration for sodium (Na, atomic number 11)?

Accepted Answer

$$[Ne] 3s^1$

Question 12

Which of the following is the empirical formula for butane ($$C_4H_{10}$$)?

Accepted Answer

$$C_2H_5$$

Question 13

A molecule has the formula $$C_5H_{10}. $$Which class of hydrocarbon could it belong to?

Accepted Answer

Cycloalkane

Question 14

Which of the following statements about the Pauli Exclusion Principle is correct?

Accepted Answer

No two electrons in the same atom can have the same set of four quantum numbers.

Question 15

Which of the following is the correct electron configuration for chromium (Cr, atomic number 24)?

Accepted Answer

$$[Ar] 4s^1$ 3d^5$

Question 16

Which of the following best describes the shape of a p orbital?

Accepted Answer

Two lobes with a node between them

Question 17

How many orbitals are present in the $$n=3$$ shell?

Accepted Answer

9

Question 18

Which of the following best describes the difference between a molecular formula and an empirical formula?

Accepted Answer

A molecular formula shows the actual number of atoms of each element in a molecule, while an empirical formula shows the simplest whole-number ratio of the elements.

Introduction to Hydrocarbons and Electronic Structure of the Atom

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