Which of the following substances could be used in galvanization of iron to prevent rusting?

Here are the solutions to the questions:

17. The general formula of an alkyl group is

• Step 1: Recall the definition of an alkyl group. An alkyl group is a functional group derived from an alkane by removing one hydrogen atom.
• Step 2: Recall the general formula for an alkane. The general formula for an alkane is $\text{C}_n\text{H}_{2n+2}$.
• Step 3: Derive the general formula for an alkyl group. By removing one hydrogen atom from an alkane, the formula becomes $\text{C}_n\text{H}_{2n+2-1}$, which simplifies to $\text{C}_n\text{H}_{2n+1}$. The correct option is C.
• C) $\text{C}_n\text{H}_{2n+1}$

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

• Step 1: Recall the molecular formula of benzene. The molecular formula of benzene is $\text{C}_6\text{H}_6$.
• Step 2: Determine the simplest ratio of carbon to hydrogen atoms. For $\text{C}_6\text{H}_6$, the ratio is $6:6$, which simplifies to $1:1$.
• Step 3: Identify the type of formula that represents the simplest whole-number ratio of atoms in a compound. This is the definition of an empirical formula. For benzene, the empirical formula is $\text{CH}$. The correct option is C.
• C) empirical formula

19. Degenerate orbitals are orbitals of

• Step 1: Define degenerate orbitals. In quantum mechanics, degenerate orbitals are atomic orbitals that have the same energy level.
• Step 2: Consider the characteristics of such orbitals. They belong to the same subshell (e.g., the three p orbitals in a given energy level, $2p_x, 2p_y, 2p_z$, all have the same energy). The correct option is D.
• 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

• Step 1: Assume the formula of the iron chloride is $\text{FeCl}_x$.
• Step 2: Write the expression for the molar mass of $\text{FeCl}_x$. $$\text{Molar mass of } \text{FeCl}_x = (\text{Molar mass of Fe}) + x \times (\text{Molar mass of Cl})$$
• Step 3: Substitute the given values into the equation. $$127 \text{ g mol}^{-1} = 56.0 \text{ g mol}^{-1} + x \times 35.5 \text{ g mol}^{-1}$$
• Step 4: Solve for $x$. $$127 - 56.0 = 35.5x$$ $$71 = 35.5x$$ $$x = \frac{71}{35.5}$$ $$x = 2$$
• Step 5: Write the formula of the chloride. Since $x=2$, the formula is $\text{FeCl}_2$. The correct option is D.
• D) $\text{FeCl}_2$

21. Which of the following substances could be used in galvanization of iron to prevent rusting?

• Step 1: Define galvanization. Galvanization is a process of applying a protective coating to iron or steel to prevent rusting.
• Step 2: Identify the common material used for galvanization. The most common and effective material used for galvanization is zinc. Zinc protects iron by acting as a sacrificial anode, corroding preferentially to iron. The correct option is A.
• A) Zinc