The simplest ratio of carbon atom to hydrogen atom in benzene represents

The general formula for an alkane is $\text{C}_n\text{H}_{2n+2}$.

An alkyl group is formed by removing one hydrogen atom from an alkane.
So, the formula becomes $\text{C}_n\text{H}_{2n+2-1} = \text{C}_n\text{H}_{2n+1}$.

• D. $\text{C}_n\text{H}_{2n+1}$

18. The simplest ratio of carbon atom to hydrogen atom in benzene represents

The molecular formula of benzene is $\text{C}_6\text{H}_6$.

The ratio of carbon to hydrogen atoms is $6:6$, which simplifies to $1:1$.

The simplest whole-number ratio of atoms in a compound is represented by its empirical formula. For benzene, the empirical formula is CH.

• C. empirical formula.

19. Degenerate orbitals are orbitals of
Degenerate orbitals are defined as orbitals that have the same energy level. For example, the three p-orbitals ($\text{p}_x, \text{p}_y, \text{p}_z$) in a given shell are degenerate.

• D. the same subshell having equal energy.

20. The molar mass of a chloride of iron is $127 \text{ g mol}^{-1}$. Given that $\text{Cl}=35.5$, $\text{Fe}=56.0$, the formula of the chloride is

Molar mass of $\text{FeCl}_x = (\text{Molar mass of Fe}) + x \times (\text{Molar mass of Cl})$
$127 = 56.0 + x \times 35.5$

$127 - 56.0 = 35.5x$
$71 = 35.5x$
$x = \frac{71}{35.5}$
$x = 2$

The formula of the chloride is $\text{FeCl}_2$.

• D. $\text{FeCl}_2$

21. Which of the following substances could be used in galvanization of iron to prevent rusting?
Galvanization is a process of applying a protective zinc coating to steel or iron to prevent rusting. Zinc is used because it is more reactive than iron and acts as a sacrificial anode, corroding in preference to the iron.

• A. Zinc

22. (The question is incomplete in the image, so I cannot provide an answer.)

23. A hydrocarbon $\text{C}_3\text{H}_y$ burns in air according to the following equation: $\text{C}_3\text{H}_{y(g)} + 5\text{O}_{2(g)} \rightarrow 3\text{CO}_{2(g)} + \frac{y}{2}\text{H}_2\text{O}_{(g)}$ The value of $y$ is

Oxygen atoms on the reactant side: $5 \times 2 = 10$ atoms.
Oxygen atoms on the product side:
From $\text{CO}_2$: $3 \times 2 = 6$ atoms.
From $\text{H}_2\text{O}$: $\frac{y}{2} \times 1 = \frac{y}{2}$ atoms.

$10 = 6 + \frac{y}{2}$

$10 - 6 = \frac{y}{2}$
$4 = \frac{y}{2}$
$y = 4 \times 2$
$y = 8$

• D. 8.

24. An element X has a valency of +3. The correct formula of its chloride is

Element X has a valency of +3.
Chlorine (Cl) is in Group 17 and typically has a valency of -1.

To balance the +3 charge of X, three chloride ions (each with a -1 charge) are needed.
The formula will be $\text{XCl}_3$.

• B. $\text{XCl}_3$

25. Y is a weak acid that turns blue and green when added to an aqueous solution of $\text{NaHSO}_4$ and $\text{Na}_2\text{CO}_3$ respectively. Y could be

$\text{NaHSO}_4$ (sodium bisulfate) is an acidic salt.
$\text{Na}_2\text{CO}_3$ (sodium carbonate) is a basic salt.

Y turns blue in an acidic solution ($\text{NaHSO}_4$).
Y turns green in a basic solution ($\text{Na}_2\text{CO}_3$).

A substance that changes color depending on the pH of the solution is an acid-base indicator.

• B. an acid-base indicator.

26. A zwitterion is
A zwitterion is a molecule that contains both positive and negative charges, but is electrically neutral overall. This characteristic of having separated positive and negative charges within the same molecule is described as being bipolar. Amino acids are common examples of zwitterions.

• D. bipolar.