JEE Chemistry Chemistry In Everyday Life MCQs Set 11

Answer: (c) The ozone layer does not permit infrared radiation from the sun to reach the earth

Explanation:
1. The ozone layer filters ultraviolet radiation; it does not block infrared radiation.
2. The other statements are correct.

Teacher's Note:
1. Stratospheric ozone absorbs UV; tropospheric greenhouse gases trap outgoing infrared.

Answer: (a) slightly lower than that of rain water without thunderstorm

Explanation:
1. Lightning makes nitrogen and oxygen of the air combine to form NO, which is oxidised to \(\ce{NO2}\) and dissolves in rain as nitric acid.
2. The extra acid lowers the pH slightly.

Teacher's Note:
1. Natural nitrogen fixation by lightning supplies nitrate to soil.

Answer: (b) 10%

Explanation:
1. Acid taken: 60 mL of M/10 \(\ce{H2SO4}\) = 60 x 0.2 = 12 mL of 1 N... i.e. 12 milliequivalents.
2. Acid left: 20 mL of M/10 NaOH = 2 milliequivalents.
3. Acid used by \(\ce{NH3}\) = 12 - 2 = 10 milliequivalents = 10 mmol of \(\ce{NH3}\) = 10 mmol N = 0.14 g.
4. Percentage of N = 0.14/1.4 x 100 = 10%.

Teacher's Note:
1. M/10 sulphuric acid is 0.2 N because it is dibasic.

Answer: (c) 23.7

Explanation:
1. HCl taken = 20 x 0.1 = 2 mmol.
2. NaOH used for the excess = 15 x 0.1 = 1.5 mmol, so excess HCl = 1.5 mmol.
3. HCl consumed by \(\ce{NH3}\) = 0.5 mmol = 0.5 mmol N = 7 mg N.
4. Percentage N = 7/29.5 x 100 = 23.7%.

Teacher's Note:
1. Moles of NH3 = acid taken minus acid left; each NH3 holds one N atom.

Answer: (c) one

Explanation:
1. EDTA is a hexadentate ligand (two N and four carboxylate O donor atoms).
2. One EDTA molecule therefore occupies all six octahedral positions of \(\ce{Ca^{2+}}\).

Teacher's Note:
1. EDTA complexes are used to remove hardness and to treat lead poisoning.

Answer: (c) Antipyretic

Explanation:
1. Antipyretics (for example paracetamol and aspirin) lower body temperature in fever.
2. Analgesics relieve pain, tranquilizers act on the mind, and antibiotics kill bacteria.

Teacher's Note:
1. Paracetamol is both an antipyretic and an analgesic.

Answer: (a) Chlorophyll is a green pigment in plants and contains calcium

Explanation:
1. Chlorophyll is a coordination compound of magnesium, not calcium.
2. Haemoglobin has iron, vitamin B12 has cobalt and carboxypeptidase-A has zinc.

Teacher's Note:
1. Remember: chlorophyll - Mg, haemoglobin - Fe, B12 - Co, carboxypeptidase - Zn.

Answer: (a) \(\ce{Fe4[Fe(CN)6]3}\)

Explanation:
1. Sodium cyanide in the extract forms sodium hexacyanoferrate(II) with ferrous sulphate.
2. Addition of \(\ce{Fe^{3+}}\) (after acidification) gives Prussian blue, \(\ce{Fe4[Fe(CN)6]3}\).

Teacher's Note:
1. Prussian blue indicates nitrogen; blood-red \(\ce{Fe(SCN)^{2+}}\) indicates N and S together.

Answer: (c) Analgesic

Explanation:
1. Aspirin relieves pain and reduces fever, so it is a non-narcotic analgesic and an antipyretic.
2. It is not an antiseptic, antibiotic or pesticide.

Teacher's Note:
1. Aspirin is made by acetylation of salicylic acid.

Answer: (b) antiseptic

Explanation:
1. Bithional is a phenolic compound that kills or prevents the growth of microorganisms on the skin; it is added to medicated soaps and toilet soaps.

Teacher's Note:
1. Antiseptics are safe for application to living tissues.

Answer: (c) aspartame

Explanation:
1. Aspartame is a dipeptide ester that decomposes at cooking temperatures, so it is used only in cold foods and drinks.
2. Saccharin, sucralose and alitame are stable on heating.

Teacher's Note:
1. Aspartame is about 100 times sweeter than cane sugar.

Answer: (a) Dilute solutions of boric acid and hydrogen peroxide are strong antiseptics

Explanation:
1. Dilute boric acid and hydrogen peroxide are weak (mild) antiseptics, so statement (a) is false.
2. Disinfectants damage living tissue, phenol is an antiseptic at 0.2% and a disinfectant at 1%, and chlorine and Lysol are strong disinfectants.

Teacher's Note:
1. Antiseptic means mild enough for skin; disinfectants are harsher.

Answer: (b) Diphenhydramine

Explanation:
1. Diphenhydramine (Benadryl) is an H1-receptor antagonist.
2. Chloramphenicol is an antibiotic, norethindrone is a progestin used in birth control pills, and omeprazole is a proton pump inhibitor used to reduce acidity.

Teacher's Note:
1. Antihistamines treat allergy; they do not affect stomach acid secretion (unlike H2 blockers).

Answer: (d) nitric acid on chloroform

Explanation:
1. Chloropicrin, \(\ce{CCl3NO2}\) (trichloronitromethane), is made by nitration of chloroform with nitric acid, or from picric acid with bleaching powder.
2. Among the options only nitric acid on chloroform is correct.

Teacher's Note:
1. Chloropicrin is used as a soil fumigant and was a war gas.

Answer: (d) Cetyltrimethylammonium bromide

Explanation:
1. Cetyltrimethylammonium bromide is a cationic surfactant: its long hydrocarbon chain forms the micelle core and the positively charged heads face water.
2. Sodium dodecyl sulphate gives anionic micelles; sodium acetate and urea are not surfactants.

Teacher's Note:
1. Micelles form above the critical micelle concentration (and above the Kraft temperature).

Answer: (a) Ampicillin is a natural antibiotic

Explanation:
1. Ampicillin is a semisynthetic modification of penicillin, not a natural antibiotic.
2. The other statements are correct (dilute phenol is both a disinfectant and an antiseptic).

Teacher's Note:
1. Natural: penicillin, tetracycline. Semisynthetic: ampicillin, amoxicillin.

Answer: (c) distillation under reduced pressure

Explanation:
1. Glycerol boils at 563 K with decomposition.
2. Under reduced pressure it distils at a much lower temperature without decomposing.

Teacher's Note:
1. Liquids that decompose near their boiling points are purified under reduced pressure.

Answer: (b) nitrate

Explanation:
1. The permissible limits are about 1-1.5 ppm for fluoride, 50 ppb for lead, 50 ppm for nitrate and 0.2-0.3 ppm for iron.
2. Fluoride is 1 ppm, lead 40 ppb and iron 0.2 ppm are within limits, but nitrate at 100 ppm is twice the limit.

Teacher's Note:
1. Convert all values to the same unit before comparing: 1000 ppb = 1 ppm.

Answer: (a) 1

Explanation:
1. Prontosil is an azo dye (it contains the -N=N- linkage), which is reduced in the body to sulphanilamide.
2. Salvarsan has As=As bonds, and sulphanilamide and sulphapyridine have no N=N link.

Teacher's Note:
1. Prontosil was the first sulpha drug; it is an azo compound.

Answer: (b) 3

Explanation:
1. Erythromycin, tetracycline and chloramphenicol inhibit growth of bacteria (bacteriostatic).
2. Penicillin and ofloxacin kill bacteria (bactericidal).

Teacher's Note:
1. Bactericidal: penicillin, aminoglycosides, ofloxacin. Bacteriostatic: tetracycline, erythromycin, chloramphenicol.

Answer: (b) 2

Explanation:
1. Chloroxylenol (4-chloro-3,5-dimethylphenol) and bithionol are phenols.
2. Terpineol is an alcohol with no hydroxyl on an aromatic ring.

Teacher's Note:
1. Dettol contains chloroxylenol and terpineol.

Answer: (b) 4

Explanation:
1. Aspartame, saccharin, sucralose and alitame are artificial sweeteners.
2. Terpineol is an antiseptic ingredient (with chloroxylenol in Dettol).

Teacher's Note:
1. Saccharin was the first artificial sweetener discovered, in 1879.