Problem 114 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following statements is correct? (a) the metal ion present in vitamin \(\mathrm{B}_{12}\) is \(\mathrm{Zn}^{2+}\) (b) in photosynthesis \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) are converted into carbohydrates in presence of sunlight (c) in haemoglobin the oxidation state of \(\mathrm{Fe}\) is \(+6\). (d) methyl salicylate is known as aspirin

Step-by-Step Solution

Answer

Statement (b) is correct.

Step 1: Identify the Options

Examine each of the provided options. We have four statements regarding vitamin B12, photosynthesis, haemoglobin, and methyl salicylate.

Step 2: Evaluate Statement (a)

Statement (a) claims that the metal ion in vitamin B12 is \(\mathrm{Zn^{2+}}\). However, vitamin B12 actually contains a cobalt ion (\(\mathrm{Co^{3+}}\)). Thus, statement (a) is incorrect.

Step 3: Evaluate Statement (b)

Statement (b) addresses the conversion of \(\mathrm{CO_2}\) and \(\mathrm{H_2O}\) into carbohydrates during photosynthesis. This is indeed correct, as photosynthesis converts carbon dioxide and water into glucose (a carbohydrate) and oxygen, in the presence of sunlight.

Step 4: Evaluate Statement (c)

Statement (c) suggests the oxidation state of iron (Fe) in haemoglobin is \(+6\). This is incorrect because the common oxidation state of iron in haemoglobin is \(+2\) when it is bound to oxygen (\(Fe^{2+}\)) and \(+3\) when it is not (\(Fe^{3+}\)).

Step 5: Evaluate Statement (d)

Statement (d) claims methyl salicylate is known as aspirin. However, this is false. Methyl salicylate is known as oil of wintergreen, while aspirin is acetylsalicylic acid.

Key Concepts

Vitamin B12

Vitamin B12 is an essential nutrient that plays a crucial role in our body's functioning. It is involved in the formation of red blood cells, DNA synthesis, and maintaining nerve health. The unique feature of Vitamin B12 is the presence of a metal ion, which is cobalt ( Co^{3+} ), distinguishing it from many other vitamins. This cobalt ion is central to the vitamin's structure, creating a coordination complex called cobalamin.

• Vitamin B12 deficiency can lead to anemia and neurological disorders.
• It is naturally found in animal products such as meat, dairy, and eggs.

People who follow plant-based diets might need to pay extra attention to their Vitamin B12 intake to prevent deficiencies.

Haemoglobin

Haemoglobin is the protein in red blood cells responsible for transporting oxygen throughout the body. Its structure is comprised of four subunits, each containing an iron atom crucial for binding oxygen. The oxidation state of iron in haemoglobin can alternate between Fe^{2+} (ferrous state) when it is oxygenated and Fe^{3+} (ferric state) when it is deoxygenated.
This change in oxidation state is important for the release and capture of oxygen as red blood cells travel through the body.

• Haemoglobin gives blood its red color.
• Inefficient haemoglobin function can lead to conditions like anemia.

Methyl Salicylate

Methyl salicylate is a naturally occurring compound commonly found in wintergreen oil. It is distinct from aspirin, which is acetylsalicylic acid. Methyl salicylate is mainly used for its pain-relieving properties and acts as a counterirritant in topical pain relief products.

• Methyl salicylate is not used internally.
• It can be toxic if ingested in large amounts.

Always use products containing methyl salicylate as directed to avoid possible irritation or poisoning.

Carbohydrates

Carbohydrates are one of the main types of nutrients and are the most important source of energy for your body. During photosynthesis, plants convert carbon dioxide and water into carbohydrates, such as glucose, in the presence of sunlight.
These carbohydrates serve as an energy source for plants and animals alike.

• Simple carbohydrates include sugars like glucose and fructose.
• Complex carbohydrates include starches and fibers found in foods like bread and pasta.

Carbohydrates play a critical role in the human diet, providing energy for daily activity.

Oxidation State

The oxidation state, also known as oxidation number, is a concept in chemistry that describes the degree of oxidation of an atom in a chemical compound. It helps in determining the electron exchange in redox reactions.
For example, in haemoglobin, iron can be in different oxidation states: Fe^{2+} and Fe^{3+} , depending on its state of oxygenation.

• Understanding oxidation states aids in balancing chemical reactions.
• Oxidation does not always involve oxygen directly; it's about the transfer of electrons.

Knowing the oxidation state is essential for predicting how elements will interact in chemical processes.

Sunlight

Sunlight is a key player in various natural processes, particularly photosynthesis, in which plants harness light energy to convert carbon dioxide and water into glucose and oxygen. This energy transfer is fundamental for life on Earth, providing the energy needed for plant growth and producing the oxygen vital for aerobic life forms.

• Sunlight is composed of a range of wavelengths, including visible light, ultraviolet, and infrared.
• It is the primary energy source for the Earth's climate system.

Understanding the role of sunlight is crucial not only in scientific contexts like photosynthesis but also in broader topics like climate change and renewable energy resources such as solar power.