Chemistry in Everyday Life - Practice Questions with Answers
75 free MCQs on Chemistry in Everyday Life, each with its own worked answer and explanation. Drugs and how they interact with biological targets, chemicals in food, and cleansing agents (soaps and detergents) - chemistry applied directly to daily life and healthcare.
75 practice questions on Chemistry in Everyday Life, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Chemistry in Everyday Life notes.
The hydrophobic hydrocarbon tail of each soap/detergent molecule dissolves into an oily dirt droplet, while the hydrophilic (ionic) head stays in the surrounding water - trapping the grease inside a micelle that rinses away with water.
Easy - 25 questions
Q1.
Equanil is a drug used mainly to reduce anxiety and stress. It is classified as a:
Branched-chain alkylbenzene sulphonate detergents are considered more environmentally problematic than their straight-chain counterparts because they are:
A Generally more expensive to manufacture on an industrial scale according to conventional understanding
B Non-biodegradable, since bacterial enzymes cannot break down the branched chain efficiently
C More acutely toxic to aquatic organisms on direct contact with the water in routine practice
D Less effective overall at removing grease and oily soils from fabric overall in most cases
Why are broad-spectrum antibiotics, such as tetracycline and chloramphenicol, sometimes used cautiously despite their effectiveness against a wide range of bacteria?
A They act against several types of bacteria, which may also disturb the population of beneficial bacteria in the body
B They are absorbed poorly by the human digestive system compared with narrow-spectrum drugs as widely reported in standard reference material
C They are effective mainly against viruses and have a limited effect on most bacterial cells under most conditions studied
D They work mainly by raising body temperature, which can feel uncomfortable for the patient in most observed cases
Soaps are generally biodegradable, but some synthetic detergents resist breakdown by microorganisms and accumulate in water bodies. What causes this difference in biodegradability?
A Soaps are made in much smaller industrial batches, which limits how much accumulates in water bodies under typical physiological conditions
B Soaps have unbranched hydrocarbon chains that microbial enzymes break down readily, unlike branched detergent chains
C Detergents carry no charge on their hydrophilic head, so they cannot interact with bacterial cell membranes according to standard texts
D Soaps dissolve in water at a faster rate, which removes them from the environment before bacteria can act in general clinical practice
Phenol is used as both an antiseptic and a disinfectant. What determines which role it plays?
A Its underlying molecular structure is said to physically rearrange itself largely between these two quite distinct chemical uses under most conditions encountered
B Concentration: a dilute solution (~0.2%) acts as an antiseptic on living tissue, while a more concentrated solution (~1%) acts as a disinfectant on inanimate objects
C It is claimed to function mainly ever as a mild antiseptic, with disinfectant-grade phenol actually being a wholly different molecule as frequently observed in practice
D The particular ambient temperature at which the phenol solution happens to be applied is what is said to determine its specific role in many documented cases according to conventional understanding
A competitive enzyme inhibitor must closely resemble the enzyme's natural substrate, but a receptor antagonist drug does not need to closely resemble the receptor's natural messenger. Why?
A Antagonist drug molecules are said to rarely actually physically bind to their intended target receptor protein, regardless of dose, timing, or the particular tissue being studied in most textbook accounts during normal conditions as generally observed
B A competitive inhibitor must fit the same active site as the substrate, requiring structural resemblance; an antagonist only needs to occupy a site (or alter the receptor's shape) that blocks activation, which does not require mimicking the natural messenger
C Enzymes are said to possess no defined catalytic active site whatsoever, with mainly cell-surface receptor proteins actually having one, according to this particular claim as generally observed under usual circumstances according to most researchers
D Receptors and enzymes are said to be largely similar chemically identical types of biological molecular targets in nearly every conceivable respect, down to the last atom in most cases according to standard textbooks in general practice
Sulphonamide drugs act as antibacterials because they competitively inhibit the bacterial enzyme that uses para-aminobenzoic acid (PABA) to synthesise folic acid. Why does this strategy harm bacteria but spare human cells?
A Sulphonamides bind to bacterial ribosomes, a structure largely absent in human cells, rather than the folic acid pathway
B Human cells get folic acid from the diet and lack the enzyme pathway that synthesises it from PABA, unlike bacteria
C Human cells break down sulphonamides into harmless products before the drug can reach any enzyme target
D Bacterial folic acid synthesis enzymes sit on the cell wall, where the drug accumulates more readily than inside human cells
Cimetidine and ranitidine are both H<sub>2</sub>-receptor antagonists used for acidity, yet they were developed to replace earlier antihistamines for allergies. Why don't ordinary (H1-blocking) antihistamines relieve stomach acidity?
A Antihistamines are broken down by stomach acid before they can act on any receptor in the gut lining
B Antihistamines for allergies block H1 receptors, while acid secretion in the stomach is controlled mainly through H<sub>2</sub> receptors
C H1 receptors are concentrated mainly in the brain, so antihistamines rarely reach the digestive tract in useful amounts
D Acidity is regulated mainly by adrenaline receptors in the stomach, which respond poorly to histamine-based drugs
Polymers used to make biodegradable sutures, such as poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV), break down inside the body over time. What structural feature of such polymers makes them susceptible to this breakdown, unlike polyethylene?
A They are built from monomers with much higher molecular mass than polyethylene, which slows their breakdown instead
B They are cross-linked thermosetting polymers, a structural feature that usually resists chemical breakdown
C They contain mainly carbon-carbon single bonds, similar to the bonds found throughout polyethylene chains
D They contain ester linkages in the backbone that can be hydrolysed by water and enzymes present in body tissue
Aspartame, a widely used artificial sweetener, is unsuitable for cooking at high temperatures and loses its sweetness over time in soft drinks. What is the chemical reason for this instability?
A It reacts with atmospheric oxygen, slowly forming a non-sweet polymer that precipitates out of solution
B It tends to sublime at the temperatures used in cooking, leaving food before it can sweeten anything
C It is a dipeptide ester, and the peptide and ester bonds in it are hydrolysed by heat and moisture
D Its sweetness relies on a metal-ion complex that breaks down on prolonged exposure to visible light
Tranquilizers and analgesics are both classified as drugs that act on the central nervous system, yet they are used for very different medical purposes. What distinguishes the primary action of a tranquilizer from that of an analgesic?
A Tranquilizers function by raising body temperature, while analgesics work by lowering blood pressure in most observed cases under typical physiological conditions
B Tranquilizers act mainly on peripheral nerves outside the brain, while analgesics act mainly within the spinal cord according to standard texts
C Tranquilizers are used mainly to treat infections of the nervous system, while analgesics treat viral infections in general clinical practice
D Tranquilizers reduce anxiety and mental tension by affecting brain neurotransmission, while analgesics mainly reduce the perception of pain
Soaps lose their cleansing action in hard water, but synthetic detergents derived from sodium salts of sulphonic acids continue to work. What underlying chemical difference explains why detergents are not affected the same way?
A Hard water ions react with detergents to form a precipitate that helps rather than hinders their cleaning action as frequently documented in most reference accounts
B Calcium and magnesium salts of sulphonic acid detergents remain soluble in water, unlike the calcium and magnesium salts of fatty acids found in soap
C Detergents carry a positive charge on their hydrophilic head, which limits how readily they react with calcium or magnesium ions under normal conditions
D Detergents have a shorter hydrophobic hydrocarbon chain, which weakens their ability to form micelles in water as generally observed in typical laboratory settings
Artificial sweeteners like saccharin and sucralose are valued for diabetic and weight-conscious diets even though many are far sweeter than table sugar. What property must such a compound have to be useful as a sweetener despite this difference in sweetness intensity?
A It must be non-nutritive, providing little caloric value, so tiny amounts match the sweetness of much more sugar
B It must contain glucose units similar to those in sucrose so the body metabolises it in a comparable way
C It must raise blood glucose levels quickly, providing the same energy boost as an equal mass of table sugar
D It must share most of table sugar's molecular structure, differing mainly by an added phosphate group
Antioxidants such as BHT (butylated hydroxytoluene) are added to fats and oils to delay rancidity. At the molecular level, how do they slow down the oxidation process that causes rancid odours and flavours?
A They lower the melting point of the fat, which slows down oxidation reactions kept at room temperature
B They donate hydrogen atoms to free radicals formed during autoxidation, interrupting the chain reaction
C They form a physical coating over the fat that limits how much oxygen reaches the fat molecules below
D They gradually convert atmospheric oxygen into carbon dioxide near the surface of the stored fat or oil