GSEB Class 12 Chemistry Solutions Chapter 16 Chemistry in Everyday Life

GSEB Class 12 Chemistry Chemistry in Everyday Life InText Questions and Answers

 

Question 1. Sleeping pills are prescribed by doctors to patients suffering from sleeplessness. However, it is not advisable to consume these doses without a doctor's consultation. Why?

Answer: Sleeping pills typically contain drugs such as tranquilizers or anti-depressants. These substances influence the nervous system, helping to alleviate anxiety, stress, irritability, or states of excitement. Nevertheless, their usage must be strictly managed under medical supervision. If taken without proper control or in excessive doses, these drugs can become harmful to both physical and mental well-being, as higher quantities can act as poisons in the body.
In simple words: Sleeping pills affect the brain to reduce stress and anxiety, but taking too many without a doctor's guidance can be dangerous and harmful because high doses are toxic.

🎯 Exam Tip: Understanding the risks associated with self-medication and the importance of professional medical advice is crucial for health-related questions.

 

Question 2. With reference to which classification has the statement, "ranitidine is an antacid" been given?

Answer: The statement "ranitidine is an antacid" is based on the drug's pharmacological effect. Ranitidine functions by preventing histamine from interacting with receptors in the stomach wall, thereby reducing the secretion of acid in the stomach. Thus, it acts as an antacid.
In simple words: Ranitidine is classified as an antacid because it stops histamine from increasing stomach acid, thereby reducing acidity.

🎯 Exam Tip: When classifying drugs, their primary mode of action and the specific condition they treat (pharmacological effect) are key criteria.

 

Question 3. Why do we require artificial sweetening agents?

Answer: Artificial sweetening agents are necessary to help reduce caloric intake and to prevent dental decay. These substances provide sweetness without the high calorie content of natural sugars and do not promote the growth of bacteria that cause cavities.
In simple words: We use artificial sweeteners to enjoy sweet tastes without consuming many calories and to protect our teeth from cavities.

🎯 Exam Tip: Focus on the two main benefits of artificial sweeteners: calorie reduction and dental health, as these are common reasons for their use.

 

Question 4. Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl palmitate. Structural formulae of these compounds are given below.
(i) \((C_{15}H_{31}COO)_3C_3H_5\) – Glyceryl palmitate
(ii) \((C_{17}H_{32}COO)_3C_3H_5\) – Glyceryl oleate

Answer:i. Glyceryl palmitate reacts with sodium hydroxide to form sodium palmitate (a soap) and glycerol: \[ (C_{15}H_{31}COO)_3C_3H_5 + 3NaOH \longrightarrow 3C_{15}H_{31}COONa + CH_2-CH-CH_2 \] \[ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad | \quad | \quad | \] \[ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad OH \quad OH \quad OH \] ii. Glyceryl oleate reacts with sodium hydroxide to form sodium oleate (a soap) and glycerol: \[ (C_{17}H_{33}COO)_3C_3H_5 + 3NaOH \longrightarrow 3C_{17}H_{33}COONa + CH_2-CH-CH_2 \] \[ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad | \quad | \quad | \] \[ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad OH \quad OH \quad OH \]
In simple words: Soap is made by reacting fats like glyceryl palmitate or glyceryl oleate with a strong base like sodium hydroxide, producing sodium soap and glycerol.

🎯 Exam Tip: Remember that saponification is the hydrolysis of an ester (like glyceryl palmitate or oleate) with a strong base, yielding a carboxylic acid salt (soap) and an alcohol (glycerol).

 

Question 5. The following type of non-ionic detergents is present in liquid detergents, emulsifying agents and wetting agents. Label the hydrophilic and hydrophobic parts in the molecule. Identify the functional group(s) present in the molecule.

Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक गैर-आयनिक डिटर्जेंट अणु की संरचना को दर्शाता है। बाईं ओर, एक लंबी हाइड्रोकार्बन श्रृंखला (\(C_9H_{19}\)) है, जिसे हाइड्रोफोबिक या गैर-ध्रुवीय भाग के रूप में लेबल किया गया है। दाईं ओर, एक एथॉक्सी समूह (\(-O(CH_2CH_2O)_xCH_2CH_2OH\)) है, जिसे हाइड्रोफिलिक या ध्रुवीय भाग के रूप में लेबल किया गया है। यह संरचना बताती है कि अणु का एक सिरा पानी से दूर रहता है और दूसरा सिरा पानी की ओर आकर्षित होता है। The molecule's structure is \(C_9H_{19}-O(CH_2CH_2O)_xCH_2CH_2OH\). The functional groups present are: - **Ether linkage** (\( -O- \)) between the alkyl chain and the polyoxyethylene chain. - **Hydroxyl group** (\( -OH \)) at the end of the polyoxyethylene chain. The parts are labeled as follows: - **Hydrophobic or non-polar part:** \(C_9H_{19}-\) (the long alkyl chain) - **Hydrophilic or polar part:** \(-O(CH_2CH_2O)_xCH_2CH_2OH\) (the polyoxyethylene chain with a terminal hydroxyl group)
In simple words: This detergent has a water-hating, oil-attracting long carbon chain (hydrophobic part) and a water-loving chain with oxygen and hydrogen (hydrophilic part) containing ether and hydroxyl functional groups.

🎯 Exam Tip: For detergents, always be ready to identify the non-polar hydrocarbon tail (hydrophobic) and the polar head group (hydrophilic), as this defines their cleansing action.

GSEB Class 12 Chemistry Chemistry in Everyday Life Text Book Questions and Answers

 

Question 1. Why do we need to classify drugs in different ways?

Answer: Drugs are classified in various ways, each serving distinct utilities:
1. **Based on Pharmacological Effect:** This classification is highly beneficial for doctors as it presents the entire spectrum of drugs available for treating a specific ailment. For instance, antacids are a class of drugs that reduce stomach acidity.
2. **Based on Drug Action:** This method categorizes drugs based on their influence on particular biochemical processes. It is useful for medicinal chemists to select appropriate 'lead compounds' when designing the synthesis of a desired drug with specific effects.
3. **Based on Chemical Structure:** This classification aids in synthesizing structurally similar compounds with varied substituents, allowing chemists to determine which variant possesses the highest effectiveness for a given therapeutic purpose.
4. **Based on Molecular Targets:** This approach is vital for medicinal chemists, enabling them to design drugs that are most effective by targeting specific receptor sites within the body.
In simple words: Drugs are classified in different ways to help doctors find treatments, guide chemists in making new drugs, and understand how they work in the body, making drug development and usage more efficient.

🎯 Exam Tip: Understanding the multiple classification criteria for drugs (pharmacological, action, structure, target) highlights their practical applications in both medicine and drug development.

 

Question 2. Explain the term, target molecules or drug targets as used in medicinal chemistry.

Answer: In medicinal chemistry, target molecules (or drug targets) refer to the biological macromolecules within the body that drugs interact with to produce a therapeutic effect.
(i) **Lead Compounds:** These are compounds that can interact with a specific target and are expected to be therapeutically active. They serve as initial starting points for designing new drugs.
(ii) **Drug Targets:** These are essential biological macromolecules such as proteins, enzymes, carbohydrates, lipids, and nucleic acids. Drugs are designed to bind to these targets, modifying their normal function to treat a disease.
In simple words: Drug targets are key molecules in our body, like proteins or enzymes, that drugs attach to and interact with to cause a specific healing effect.

🎯 Exam Tip: When defining drug targets, emphasize that they are biological macromolecules (proteins, enzymes, etc.) and explain their role in drug-receptor interactions.

 

Question 3. Name the macromolecules that are chosen as drug targets.

Answer: Macromolecules such as proteins, enzymes, nucleic acids, carbohydrates, and lipids are typically selected as drug targets due to their critical roles in biological processes.
In simple words: Proteins, enzymes, nucleic acids, carbohydrates, and lipids are the main large molecules in the body that drugs are designed to interact with.

🎯 Exam Tip: List all five types of macromolecules (proteins, enzymes, nucleic acids, carbohydrates, lipids) when asked to identify drug targets.

 

Question 4. Why should not medicines be taken without consulting doctors?

Answer: It is crucial not to take medicines without consulting a doctor for several reasons: many drugs can have harmful effects if taken in doses higher than recommended, essentially acting as poisons. Furthermore, side effects can arise when a drug binds to multiple receptor sites in the body, affecting unintended physiological processes. Therefore, medical consultation is essential to ensure proper dosage and minimize adverse reactions.
In simple words: Medicines can be harmful or even poisonous in incorrect doses, and they might cause unexpected side effects by acting on different parts of the body, so always consult a doctor.

🎯 Exam Tip: Highlight the two main dangers of self-medication: overdose leading to toxicity and unintended side effects from non-specific binding.

 

Question 5. Define the term chemotherapy.

Answer: Chemotherapy is a branch of chemistry focused on treating diseases using specific chemicals. It involves the use of chemical agents to inhibit the growth of or kill disease-causing cells or microorganisms.
In simple words: Chemotherapy is the medical treatment of diseases, especially cancer and infections, using specific chemical substances.

🎯 Exam Tip: Define chemotherapy precisely as the treatment of diseases using chemicals, often emphasizing its application in cancer and microbial infections.

 

Question 6. Which forces are involved in holding the drugs to the active site of enzymes?

Answer: Drugs are held to the active sites of enzymes through various intermolecular forces. These include hydrogen bonding, ionic bonding, dipole-dipole interactions, and van der Waals interactions. These forces collectively ensure the drug's specific and temporary binding to the enzyme.
In simple words: Drugs bind to enzymes using weak attractions like hydrogen bonds, ionic bonds, dipole interactions, and van der Waals forces.

🎯 Exam Tip: Remember the four main types of intermolecular forces: hydrogen bonding, ionic bonding, dipole-dipole interactions, and van der Waals forces, as they are fundamental to drug-receptor binding.

 

Question 7. While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other?

Answer: Antacids and antiallergic drugs, despite both interacting with histamine, do not interfere with each other's functions because they target different types of histamine receptors. Histamine can cause both allergic reactions and increased stomach acid release. Antihistamines block the receptors responsible for allergy symptoms, while antacids (specifically H2-blockers like ranitidine) block the receptors responsible for stimulating HCl secretion in the stomach. Since they act on distinct receptors, their therapeutic effects are separate.
In simple words: Antacids and antiallergic drugs both affect histamine, but they target different histamine receptors in the body, so they don't block each other's actions.

🎯 Exam Tip: The key differentiator here is "different receptors." Emphasize that drugs are specific to certain receptor types, even if they act on the same signaling molecule.

 

Question 8. Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs.

Answer: Noradrenaline, a vital neurotransmitter, is associated with mood regulation, and a low level of it can lead to depression. This condition is typically treated with antidepressant drugs. These medications work by inhibiting the enzymes that break down noradrenaline, thereby allowing noradrenaline to remain active at its receptors for longer periods, which helps to counteract depression. Examples of such antidepressants include Iproniazid and Phenelzine.
In simple words: Low noradrenaline causes depression; antidepressant drugs like Iproniazid and Phenelzine are used to fix this by increasing noradrenaline levels in the brain.

🎯 Exam Tip: Associate low noradrenaline with depression and identify antidepressants as the treatment class, along with specific examples like Iproniazid and Phenelzine.

 

Question 9. What is meant by the term 'broad spectrum antibiotics'? Explain.

Answer: Broad spectrum antibiotics are a class of antimicrobial drugs effective against a wide range of microorganisms, including both Gram-positive and Gram-negative bacteria. For example, Tetracycline and Chloramphenicol are broad spectrum antibiotics. Chloramphenicol, in particular, is highly versatile and can be used to treat various infections such as typhoid, dysentery, acute fever, urinary tract infections, meningitis, and pneumonia.
In simple words: Broad spectrum antibiotics are medicines that kill or stop the growth of many different types of bacteria, not just a few specific ones.

🎯 Exam Tip: Define broad spectrum antibiotics by their ability to act on a wide range of microorganisms and provide key examples like Tetracycline or Chloramphenicol.

 

Question 10. How do antiseptics differ from disinfectants? Give one example of each.

Answer: Antiseptics and disinfectants are both antimicrobial agents, but they differ in their application and toxicity:
**Antiseptics:**
- They are generally safe for living tissues and are applied to prevent or kill harmful microorganisms on the skin.
- They are used on wounds, ulcers, or diseased skin surfaces.
- Example: Iodine, Boric acid.
**Disinfectants:**
- They are toxic to living tissues and are primarily used to destroy harmful microorganisms on inanimate objects.
- They are employed for disinfecting floors, toilets, drains, and instruments.
- Example: Phenol.
In simple words: Antiseptics are safe for skin and kill germs on living tissues (like iodine), while disinfectants are toxic to skin but kill germs on non-living surfaces (like phenol).

🎯 Exam Tip: The critical distinction between antiseptics and disinfectants lies in their application: living tissue vs. inanimate objects. Provide a clear example for each.

 

Question 11. Why are cimetidine and ranitidine better antacids than sodium hydrogen carbonate or magnesium or aluminium hydroxide?

Answer: Cimetidine and ranitidine are superior antacids compared to sodium hydrogen carbonate, magnesium hydroxide, or aluminium hydroxide because they prevent the interaction of histamine with receptor cells in the stomach wall, thereby significantly reducing the release of hydrochloric acid (HCl). In contrast, traditional antacids like sodium hydrogen carbonate, magnesium hydroxide, or aluminium hydroxide work by neutralizing existing stomach acid. However, the excessive use of these traditional antacids can make the stomach overly alkaline, which paradoxically triggers the release of even more HCl, potentially leading to ulcers in the stomach.
In simple words: Cimetidine and ranitidine are better because they stop the stomach from producing too much acid in the first place, while older antacids just neutralize existing acid, which can sometimes make the stomach produce even more acid later.

🎯 Exam Tip: Focus on the mechanism of action: cimetidine/ranitidine *prevent* acid secretion (receptor blockers), while traditional antacids *neutralize* existing acid, which can cause a rebound effect.

 

Question 12. Name a substance which can be used as an antiseptic as well as disinfectant.

Answer: Phenol is a substance that can function as both an antiseptic and a disinfectant. A 0.2% solution of phenol acts as an antiseptic, while a 1% solution of phenol acts as a disinfectant.
In simple words: Phenol can be an antiseptic at low concentrations (0.2%) for skin, and a disinfectant at higher concentrations (1%) for surfaces.

🎯 Exam Tip: Remember that phenol's concentration determines its use as an antiseptic or disinfectant. 0.2% is antiseptic, 1% is disinfectant.

 

Question 13. What are the main constituents of dettol?

Answer: The primary active constituents of Dettol are Chloroxylenol and α-Terpineol, dissolved in a suitable solvent.
In simple words: Dettol is mainly made of Chloroxylenol and alpha-Terpineol mixed in a liquid.

🎯 Exam Tip: Identify Chloroxylenol and α-Terpineol as the two main active ingredients of Dettol.

 

Question 14. What is tincture of iodine? What is its use?

Answer: Tincture of iodine refers to a 2-3% solution of iodine mixed in an alcohol-water solvent. It is primarily used as an antiseptic to clean wounds and prevent infections.
In simple words: Tincture of iodine is a 2-3% iodine solution in alcohol and water, used as an antiseptic to clean injuries.

🎯 Exam Tip: Remember the composition (iodine in alcohol-water mixture) and primary use (antiseptic) for tincture of iodine.

 

Question 15. What are food preservatives?

Answer: Food preservatives are chemical substances employed to prevent food spoilage caused by microbial growth and undesirable chemical changes. These substances extend the shelf life of food products. An example is Sodium benzoate.
In simple words: Food preservatives are chemicals added to food to stop microbes from growing and spoiling it, helping the food last longer.

🎯 Exam Tip: Define food preservatives by their function (preventing microbial growth and spoilage) and provide a common example like sodium benzoate.

 

Question 16. Why is use of aspartame limited to cold foods and drinks?

Answer: The use of aspartame is restricted to cold foods and drinks because it decomposes when exposed to baking or cooking temperatures. Its chemical structure breaks down under heat, leading to a loss of sweetness and potentially altering its properties.
In simple words: Aspartame can only be used in cold foods and drinks because it breaks down when heated, losing its sweetness.

🎯 Exam Tip: The key reason for aspartame's limited use is its thermal instability, meaning it decomposes at high temperatures.

 

Question 17. What are artificial sweetening agents? Give two examples.

Answer: Artificial sweetening agents are chemical substances that provide a sweet taste similar to sugar but have negligible or zero caloric content. They are used as sugar substitutes, especially for individuals managing calorie intake or diabetes. Examples include Saccharin and Aspartame.
In simple words: Artificial sweeteners are chemicals that taste sweet but have almost no calories, like Saccharin and Aspartame.

🎯 Exam Tip: Define artificial sweeteners by their calorie-free sweetness and provide at least two common examples like Saccharin and Aspartame.

 

Question 18. Name the sweetening agent used in the preparation of sweets for a diabetic patient.

Answer: Aspartame is a common sweetening agent used in the preparation of sweets for diabetic patients, as it provides sweetness without affecting blood sugar levels.
In simple words: Aspartame is the sweetener used for diabetic patients.

🎯 Exam Tip: Aspartame is a key example for diabetic-friendly sweeteners; recognize its specific application.

 

Question 19. What problem arises in using alitame as artificial sweetener?

Answer: The main challenge with using alitame as an artificial sweetener is its extremely high potency. Alitame is approximately 2000 times sweeter than cane sugar, making it very difficult to precisely control the level of sweetness when adding it to food or beverages.
In simple words: Alitame is so much sweeter than sugar that it's very hard to add the correct amount without making food too sweet.

🎯 Exam Tip: The extreme sweetness and difficulty in dosage control are the primary issues with alitame as a sweetener.

 

Question 20. How are synthetic detergents better than soaps?

Answer: Synthetic detergents are superior to soaps primarily because their cleansing action is not negatively affected by the presence of \(Ca^{2+}\) and \(Mg^{2+}\) ions found in hard water. Soaps, on the other hand, react with these ions to form insoluble precipitates (scum), which reduces their effectiveness and leaves behind a gummy residue. Therefore, unlike soaps, synthetic detergents work well even in hard water.
In simple words: Synthetic detergents work better than soaps because they don't form scum or become ineffective in hard water, unlike soaps.

🎯 Exam Tip: The main advantage of synthetic detergents over soaps is their ability to work effectively in hard water without forming insoluble precipitates.

 

Question 21. Explain the following terms with suitable examples
(i) Cationic detergents
(ii) Anionic detergents
(iii) Non-ionic detergents.

Answer:
(i) **Cationic detergents:** These are surface-active detergents characterized by a cationic (positively charged) hydrophilic part. Cationic detergents are typically quaternary ammonium salts of amines, where the cationic part contains a long hydrocarbon chain and a positive charge on the nitrogen atom. They are used in hair conditioners due to their germicidal properties but are generally more expensive.
(ii) **Anionic detergents:** These are surface-active detergents that possess an anionic (negatively charged) hydrophilic group. Sodium salts of alkyl benzenesulfonates are a significant class of anionic detergents. They are widely used for household cleaning and also found in toothpastes.
(iii) **Non-ionic detergents:** These detergents have no ionic charge; instead, they contain polar groups capable of forming hydrogen bonds with water. Polyethylene glycol reacting with stearic acid is an example of a reaction forming non-ionic detergents. These detergents are used in liquid detergents, emulsifying agents, and wetting agents. Their cleansing mechanism is similar to soaps, and they are increasingly popular for cleaning synthetic fibers due to their effectiveness.
ℹ️ चित्र व्याख्या (Diagram Explanation):**Cationic Detergent Example:** यह संरचना सेटील्ट्राइमिथाइल अमोनियम ब्रोमाइड (Cetyltrimethyl ammonium bromide) को दर्शाती है। इसमें एक लंबी हाइड्रोकार्बन श्रृंखला (\(CH_3(CH_2)_{15}\)) है जो हाइड्रोफोबिक हिस्सा है, और एक धनात्मक आवेशित चतुष्कोणीय अमोनियम आयन (\( -N^+(CH_3)_3Br^-\)) है जो हाइड्रोफिलिक हिस्सा है। यह अणु की रोगाणुनाशक प्रकृति को दर्शाता है। \( CH_3(CH_2)_{15}-N^+(CH_3)_3Br^- \) **Anionic Detergent Example:** ये दो संरचनाएं आयनिक डिटर्जेंट के उदाहरण हैं। पहली सोडियम डोडेसिल सल्फेट (Sodium dodecyl sulphate) है (\(C_{12}H_{25}OSO_3^-Na^+\)), जहाँ लंबी कार्बन श्रृंखला (\(C_{12}H_{25}\)) हाइड्रोफोबिक है और सल्फेट समूह (\(OSO_3^-Na^+\)) हाइड्रोफिलिक है। दूसरी सोडियम-p-डोडेसिल बेंजीन सल्फोनेट (Sodium-p-dodecyl benzene sulphonate) है (\(C_{12}H_{25}-\phi-SO_3^-Na^+\)), जहाँ डोडेसिल बेंजीन भाग हाइड्रोफोबिक है और सल्फोनेट समूह (\(SO_3^-Na^+\)) हाइड्रोफिलिक है। **Non-ionic Detergent Formation:** यह एक गैर-आयनिक डिटर्जेंट के निर्माण की रासायनिक प्रतिक्रिया को दर्शाता है। इसमें स्टीयरिक एसिड (\(CH_3(CH_2)_{16}COOH\)) पॉलीइथाइलीन ग्लाइकोल (\(HO(CH_2CH_2O)_nCH_2CH_2OH\)) के साथ प्रतिक्रिया करके एक गैर-आयनिक डिटर्जेंट (\(CH_3(CH_2)_{16}COO(CH_2CH_2O)_nCH_2CH_2OH\)) बनाता है। इस प्रक्रिया में पानी निकलता है। अंतिम उत्पाद में एस्टर लिंकेज और ईथर लिंकेज होते हैं, और लंबी पॉलीऑक्सीएथिलीन श्रृंखला हाइड्रोफिलिक होती है। \[ CH_3(CH_2)_{16}COOH + HO(CH_2CH_2O)_nCH_2CH_2OH \xrightarrow{-H_2O} CH_3(CH_2)_{16}COO(CH_2CH_2O)_nCH_2CH_2OH \]
In simple words: Cationic detergents have a positive charged head (like in hair conditioners), anionic detergents have a negative charged head (like in laundry soaps), and non-ionic detergents have no charge but still have water-attracting parts (like in liquid dish soaps).

🎯 Exam Tip: For each detergent type, define its hydrophilic part's charge (cationic, anionic, non-ionic) and give a relevant example. Knowing their structural features (e.g., quaternary ammonium salts for cationic) is also valuable.

 

Question 22. What are biodegradable and non-biodegradable detergents? Give one example of each.

Answer:
(i) **Biodegradable detergents:** These are detergents that have straight hydrocarbon chains. Their structure allows them to be easily broken down or decomposed by microorganisms in the environment. This characteristic makes them environmentally friendly.
Example: Sodium lauryl sulfate, sodium 4-(1-dodecyl) benzene sulfonate, sodium 4-(2-dodecyl) benzene sulfonate.
(ii) **Non-biodegradable detergents:** These detergents contain branched hydrocarbon chains. The branching hinders their degradation by microorganisms, meaning they persist in the environment for longer periods. This leads to environmental pollution, particularly foaming in rivers and waterways.
Example: Sodium 4-(1,3,5,7-tetramethyloctyl) benzenesulphonate.
In simple words: Biodegradable detergents can be broken down by microbes because they have straight carbon chains, while non-biodegradable detergents have branched chains that resist microbial breakdown, causing pollution.

🎯 Exam Tip: The key distinction is the nature of the hydrocarbon chain: straight chains are biodegradable, while branched chains lead to non-biodegradability. Provide an example for each category.

 

Question 23. Why do soaps not work in hard water?

Answer: Soaps are ineffective in hard water because hard water contains high concentrations of \(Ca^{2+}\) and \(Mg^{2+}\) ions. When soaps are used in hard water, these metal ions react with the soap molecules to form insoluble calcium and magnesium salts of fatty acids. These insoluble precipitates, often referred to as scum, do not have cleansing properties and tend to stick to clothes as a gummy mass, hindering the washing process.
In simple words: Soaps don't work in hard water because the calcium and magnesium ions in hard water react with soap to form insoluble scum, which doesn't clean and leaves a residue.

🎯 Exam Tip: Explain that the presence of \(Ca^{2+}\) and \(Mg^{2+}\) ions in hard water causes soaps to precipitate as insoluble salts (scum), making them ineffective for cleansing.

 

Question 24. Can you use soaps and synthetic detergents to check the hardness of water?

Answer: Yes, you can use both soaps and synthetic detergents to check for water hardness, but with different observations. Soaps precipitate as insoluble calcium and magnesium salts when present in hard water, forming visible scum. In contrast, synthetic detergents do not form such precipitates in hard water. Therefore, by observing whether lather is formed easily or if scum is produced, one can infer the hardness of the water.
In simple words: Yes, you can check water hardness: soaps will form scum in hard water, but synthetic detergents will not.

🎯 Exam Tip: The formation of scum with soap is a clear indicator of hard water, while synthetic detergents' ability to lather freely indicates either soft or hard water (as they work in both).

 

Question 25. If water contains dissolved calcium hydrogen carbonate, out of soaps and synthetic detergents which one will you use for cleaning clothes?

Answer: If water contains dissolved calcium hydrogen carbonate, it is considered hard water. In this scenario, synthetic detergents would be the preferred choice for cleaning clothes. Soaps are unsuitable because the \(Ca^{2+}\) ions from calcium bicarbonate would react with soap molecules to form insoluble precipitates, rendering the soap ineffective for cleansing. Synthetic detergents, however, do not form such precipitates in hard water and can therefore clean effectively.
In simple words: For hard water containing calcium hydrogen carbonate, synthetic detergents are better for cleaning clothes than soaps because soaps form ineffective scum in hard water.

🎯 Exam Tip: Reiterate the advantage of synthetic detergents in hard water: they prevent scum formation, ensuring effective cleaning where soaps fail.

 

Question 26. Label the hydrophilic and hydrophobic parts in the following compounds.
(a) \(CH_3(CH_2)_{10}CH_2OSO_3^-Na^+\)
(b) \(CH_3(CH_2)_{15}N^+(CH_3)_3Br^-\)
(c) \(CH_3(CH_2)_{16}COO(CH_2CH_2O)_nCH_2CH_2OH\)

Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation):**कंपाउंड (a):** इस संरचना में, लंबी हाइड्रोकार्बन श्रृंखला \(CH_3(CH_2)_{10}CH_2-\) हाइड्रोफोबिक या गैर-ध्रुवीय भाग है। सल्फेट समूह (\(-OSO_3^-Na^+\)) पानी में घुलनशील होने के कारण हाइड्रोफिलिक या ध्रुवीय भाग है। **कंपाउंड (b):** इस अणु में, \(CH_3(CH_2)_{15}-\) लंबी कार्बन श्रृंखला हाइड्रोफोबिक हिस्सा है। धनात्मक आवेशित चतुष्कोणीय अमोनियम आयन (\(-N^+(CH_3)_3Br^-\)) हाइड्रोफिलिक हिस्सा है। **कंपाउंड (c):** इस संरचना में, \(CH_3(CH_2)_{16}-\) लंबी अल्काइल श्रृंखला हाइड्रोफोबिक हिस्सा है। एस्टर और पॉलीऑक्सीएथिलीन श्रृंखला वाला भाग (\(-COO(CH_2CH_2O)_nCH_2CH_2OH\)) हाइड्रोफिलिक हिस्सा है।
(a) \(CH_3(CH_2)_{10}CH_2OSO_3^-Na^+\)
Hydrophobic part: \(CH_3(CH_2)_{10}CH_2-\)
Hydrophilic part: \(-OSO_3^-Na^+\)
(b) \(CH_3(CH_2)_{15}N^+(CH_3)_3Br^-\)
Hydrophobic part: \(CH_3(CH_2)_{15}-\)
Hydrophilic part: \(-N^+(CH_3)_3Br^-\)
(c) \(CH_3(CH_2)_{16}COO(CH_2CH_2O)_nCH_2CH_2OH\)
Hydrophobic part: \(CH_3(CH_2)_{16}-\)
Hydrophilic part: \(-COO(CH_2CH_2O)_nCH_2CH_2OH\)
In simple words: For each compound, the long hydrocarbon chain is the water-hating (hydrophobic) part, and the charged or oxygen-rich group (sulfate, ammonium, ester-polyoxyethylene) is the water-loving (hydrophilic) part.

🎯 Exam Tip: To label hydrophilic and hydrophobic parts, identify the long non-polar hydrocarbon chain as hydrophobic and the polar, often charged, functional group as hydrophilic.

GSEB Class 12 Chemistry Chemistry in Everyday Life Additional Important Questions and Answers

 

Question 1. The discovery of antibiotics makes the treatment of diseases very easy.
(i) What do you understand by 'antibiotics'?
(ii) Which was the first antibiotic and who discovered it?
(iii) How are the antibiotics classified?
(iv) Write a note on sulpha drugs.

Answer:
(i) **Antibiotics** are chemical substances, typically produced by microorganisms, that can either inhibit the growth of or completely destroy other harmful microorganisms (like bacteria) without causing significant damage to the host.
(ii) The first antibiotic ever discovered was **penicillin**, isolated by **Alexander Fleming** in 1929 from a mold known as *Penicillium notatum*.
(iii) Antibiotics are primarily classified into two main categories based on their spectrum of activity:
- **Narrow spectrum antibiotics:** These are effective only against a limited range of microorganisms. An example is penicillin, which primarily targets Gram-positive bacteria.
- **Broad spectrum antibiotics:** These substances are active against a wide array of microorganisms, including both Gram-positive and Gram-negative bacteria. Examples include tetracycline and chloramphenicol.
(iv) **Sulpha drugs** represent the first class of effective chemotherapeutic agents. They were widely utilized to treat bacterial infections such as pneumonia, tuberculosis, and diphtheria. Their mechanism involves the bacteria responsible for the disease absorbing the sulpha drugs, which then interferes with their metabolic processes, halting their growth and further multiplication. These drugs are typically derivatives of sulfanilamide, with examples including sulfadiazine and sulfathiazole.
In simple words: Antibiotics are microbe-made chemicals that fight infections; Penicillin was the first, discovered by Fleming. They are classified as narrow or broad-spectrum based on how many types of germs they kill. Sulpha drugs were early chemotherapies that stop bacterial growth.

🎯 Exam Tip: For antibiotics, define them, recall penicillin's discovery, understand the difference between narrow and broad-spectrum, and remember sulpha drugs as early chemotherapeutic agents.

 

Question 2. What are antihistamines? Give two examples

Answer: **Antihistamines** are drugs that either reduce or inhibit the action of histamine in the body, thereby preventing allergic reactions. Histamines are chemicals released during allergic responses, causing symptoms like itching, sneezing, and watery eyes. Two important examples of antihistamines are Brompheniramine and Terfenadine.
**Mode of action:** Histamines interact with specific binding sites on receptors in the body to trigger allergy symptoms. Antihistamines work by competing with histamines for these receptor binding sites. By occupying these sites, antihistamines prevent histamine from binding and producing its allergic effects.
In simple words: Antihistamines are drugs that stop allergic reactions by blocking histamine from acting on its receptors; Brompheniramine and Terfenadine are examples.

🎯 Exam Tip: Define antihistamines by their function (reducing histamine action to prevent allergies) and mechanism (competing for receptor sites). Provide specific examples.

 

Question 3. Match the following.

A	B
i. Antipyretic	a. Phenol
ii. Analgesic	b. Barbituric acid
iii. Antibiotic	c. Brufen
iv. Tranquillizer	d. Aspirin
v. Antiseptic	e. Penicillin
vi. Disinfectant	f. Iodoform

Answer:
i. d
ii. c
iii. e
iv. b
v. f
vi. a
In simple words: This question matches drug categories with their examples: Antipyretics (fever reducers) with Aspirin, Analgesics (pain relievers) with Brufen, Antibiotics (germ killers) with Penicillin, Tranquillizers (calming agents) with Barbituric acid, Antiseptics (for living tissue) with Iodoform, and Disinfectants (for surfaces) with Phenol.

🎯 Exam Tip: For matching questions, clearly understand the definition and primary function of each drug category (e.g., antipyretic for fever, analgesic for pain) and its representative example.

 

Question 4. What is the nature of an antacid?

Answer: An antacid is a substance that works to reduce or neutralize excess hydrochloric acid (HCl) in the stomach. Modern antacids, such as cimetidine and ranitidine, achieve this by preventing histamine from interacting with receptors present in the stomach wall, thereby inhibiting acid release.
In simple words: Antacids are medicines that reduce stomach acid, either by neutralizing it or by stopping its production, like cimetidine and ranitidine.

🎯 Exam Tip: Focus on the dual nature of antacids: either neutralizing existing acid or blocking its production by interacting with receptors.