Question

The compound which does not show a simple ratio of atoms is:

• A. Benzene
• B. Acetylene
• C. Hydrogen
• D. Sucrose

Hint:

Sucrose is a disaccharide with a complex molecular structure and does not exhibit a simple ratio of atoms like elemental substances.

Answer 1

The Correct Option is D

• Option 1: Benzene - This is incorrect. Benzene (C₆H₆) has a 1:1 ratio of carbon to hydrogen atoms, which may appear complex due to its aromatic ring structure, but it still follows a simple atomic ratio of 1:1 in terms of carbon and hydrogen atoms.
• Option 2: Acetylene - This is incorrect. Acetylene (C₂H₂) follows a simple atomic ratio of 1:1 for carbon to hydrogen atoms, which makes it a straightforward molecule with a simple ratio of atoms.
• Option 3: Hydrogen - This is incorrect. Hydrogen (H₂) is a simple diatomic molecule with a 1:1 atomic ratio of hydrogen atoms.
• Option 4: Sucrose - This is the correct answer. Sucrose (C₁₂H₂₂O₁₁) does not follow a simple atomic ratio due to its more complex molecular structure. While the ratio of carbon to hydrogen to oxygen in sucrose is a whole number (12:22:11), it is considered more intricate because of the way the atoms are bonded in the molecule. The atomic arrangement in sucrose involves multiple functional groups and glycosidic linkages between monosaccharide units (glucose and fructose), which makes the ratio appear more complex compared to simple molecular compounds like acetylene or benzene.

Detailed Explanation: 

Sucrose is a disaccharide made up of two monosaccharides: glucose and fructose. The molecular formula of sucrose is C₁₂H₂₂O₁₁, which gives the atomic ratio of 12:22:11. While this is still a simple whole number ratio, the structure is far more complex than simple molecular compounds like acetylene (C₂H₂) or hydrogen (H₂). In sucrose, the atoms are arranged in a way that involves glycosidic bonds between glucose and fructose units. These bonds introduce additional complexity in the molecular structure, making the atomic ratio not as simple in terms of bonding and molecular arrangement.

In simpler molecules such as acetylene, each carbon is bonded to two hydrogens, and the molecule is linear. In benzene, although it involves resonance and an aromatic ring, the atomic ratio between carbon and hydrogen remains 1:1. On the other hand, sucrose's molecular structure includes more functional groups, and the carbon-to-hydrogen-to-oxygen ratio becomes complicated by the way the atoms are connected within the molecule.

Answer 2

Grouping these four substances by what kind of compound they actually are shows why one of them stands apart from the rest structurally.

1. Benzene: This is a single ring hydrocarbon with formula C6H6, a straightforward 1 is to 1 ratio of carbon to hydrogen atoms in one simple ring structure.
2. Acetylene: This is a small two-carbon hydrocarbon with formula C2H2, again a plain 1 is to 1 ratio of carbon to hydrogen in a single small molecule.
3. Hydrogen: This is the simplest possible molecule of all, H2, just two identical atoms bonded together with nothing else to consider.
4. Sucrose: Unlike the three above, sucrose is not one simple small molecule, it is a disaccharide, glucose and fructose joined together by a glycosidic bond, giving the formula C12H22O11. Its atomic ratio comes from combining two separate sugar units rather than from one uniform repeating structure, which makes its atomic makeup far less straightforward than the other three.

Being assembled from two joined sugar units rather than existing as a single small, uniform molecule is what makes sucrose's atomic arrangement the odd one out here.

So the correct answer is Sucrose.