Science and Technology: Unit-wise Objective Question Bank

Group A of the SEE Science and Technology paper is ten multiple-choice questions, and Group B adds nine very short one-mark questions. Together they are 19 of the 75 marks, and they can be secured in about half an hour. This chapter drills all 19 textbook chapters in order. Each section opens with a short facts line (what the objective questions keep returning to), then gives seven MCQs, then a key in which every answer has a one-line reason.

2.1 Scientific Learning

Facts. The SI unit of length is the metre, of mass the kilogram, of time the second. A scientific method runs: observation, problem, hypothesis, experiment, analysis, conclusion. A hypothesis is a testable guess.

1. The correct order of the scientific method after observing a problem is [1]aconclusion, hypothesis, experimentbhypothesis, experiment, conclusioncexperiment, hypothesis, conclusiondhypothesis, conclusion, experiment
2. A tentative, testable explanation of an observation is called a [1]atheoryblawchypothesisdconclusion
3. The SI unit of mass is the [1]agrambkilogramcpounddquintal
4. A length of 2.5 km, expressed in metres, is [1]a25 mb250 mc2500 md25000 m
5. The variable that the experimenter deliberately changes is the [1]adependent variablebcontrolled variablecindependent variabledconstant
6. Which instrument measures the volume of an irregular solid by displacement? [1]ameasuring cylinderbspring balancecstopwatchdthermometer
7. A project report should end with [1]athe titlebthe conclusion and recommendationscthe objectivesdthe acknowledgement

Answers

1. (b) — a hypothesis is stated, then tested by an experiment, then judged in the conclusion.

2. (c) — a hypothesis is a testable guess; a theory is already well tested.

3. (b) — the kilogram is the SI base unit of mass; the gram is a sub-unit.

4. (c) — 2.5\times1000=2500 m.

5. (c) — the independent variable is the one the experimenter changes.

6. (a) — a measuring cylinder shows the water level before and after immersion.

7. (b) — a report closes with findings, conclusion and recommendations.

2.2 Classification of Living Beings

Facts. Whittaker proposed five kingdoms in 1969: Monera, Protista, Fungi, Plantae, Animalia. Linnaeus gave binomial nomenclature (genus then species). Fungal cell walls are made of chitin.

1. The five-kingdom classification was proposed by [1]aLinnaeusbAristotlecWhittakerdMendel
2. Which kingdom contains organisms without a true nucleus? [1]aProtistabFungicPlantaedMonera
3. The cell wall of fungi is made of [1]acellulosebchitincpeptidoglycan onlydlignin
4. In the name Homo sapiens, sapiens is the [1]agenusbfamilycspeciesdorder
5. Amoeba belongs to the kingdom [1]aMonerabProtistacFungidAnimalia
6. Which pair is correctly matched? [1]amushroom, Plantaebbacteria, Protistacyeast, Fungidfern, Animalia
7. An organism that makes its own food and has a cell wall of cellulose is placed in [1]aFungibPlantaecMoneradAnimalia

Answers

1. (c) — R. H. Whittaker, 1969.

2. (d) — Monera are prokaryotes: no nuclear membrane.

3. (b) — chitin is the fungal wall material; cellulose belongs to plants.

4. (c) — the first word is the genus (Homo), the second the species.

5. (b) — Amoeba is a single-celled eukaryote, so it is a protist.

6. (c) — yeast is a unicellular fungus; a mushroom is a fungus, bacteria are Monera and ferns are plants.

7. (b) — plants are autotrophs with cellulose cell walls.

2.3 Honey Bee

Facts. Castes: queen, worker, drone. Development from egg to adult takes 16 days (queen), 21 (worker), 24 (drone). Only Apis cerana and Apis mellifera are kept in hives. Honey bees belong to class Insecta, order Hymenoptera.

1. The only egg-laying female of a bee colony is the [1]aworkerbdronecqueendnurse bee
2. A drone develops from egg to adult in [1]a16 daysb21 daysc24 daysd30 days
3. Which species is domesticated and native to Nepal? [1]aApis dorsatabApis ceranacApis floreadApis laboriosa
4. The main duty of the drone is to [1]acollect nectarbbuild the combcmate with the queendguard the hive
5. The sac in which the queen stores sperm is the [1]acropbspermathecacsting glanddpollen basket
6. Honey bees belong to the order [1]aLepidopterabDipteracHymenopteradColeoptera
7. The correct order of the bee life cycle is [1]aegg, pupa, larva, adultbegg, larva, pupa, adultclarva, egg, pupa, adultdegg, larva, adult, pupa

Answers

1. (c) — workers are sterile females; the queen lays all eggs.

2. (c) — queen 16, worker 21, drone 24 days.

3. (b) — Apis cerana is native and kept in hives; A. dorsata and A. florea are wild.

4. (c) — a drone mates with a virgin queen and dies afterwards.

5. (b) — the spermatheca keeps sperm alive for her whole life.

6. (c) — bees, wasps and ants are Hymenoptera.

7. (b) — complete metamorphosis: egg, larva, pupa, adult.

2.4 Heredity

Facts. Mendel worked on the garden pea. A monohybrid F₂ ratio is 3 : 1 (phenotype) and 1 : 2 : 1 (genotype); a dihybrid ratio is 9 : 3 : 3 : 1. Humans have 46 chromosomes (23 pairs); females are XX, males XY. Down syndrome is trisomy 21 (47 chromosomes).

1. The father of genetics is [1]aDarwinbMendelcLamarckdWatson
2. The phenotypic ratio of a monohybrid cross in F₂ is [1]a1 : 1b1 : 2 : 1c3 : 1d9 : 3 : 3 : 1
3. A cross of Tt × Tt gives tall (T is dominant) and dwarf offspring in the ratio [1]a1 : 3b3 : 1c1 : 1d2 : 1
4. The sex chromosomes of a human female are [1]aXYbXXcYYdXO
5. The sex of a child is decided by the chromosome contributed by the [1]amotherbfathercboth equallydgrandparents
6. Down syndrome results from [1]athree copies of chromosome 21bone X chromosome missingca recessive gene on Xdan extra Y chromosome
7. Colour blindness is more common in males because the gene is [1]aon the Y chromosomebdominantcrecessive and on the X chromosomedon chromosome 21

Answers

1. (b) — Gregor Mendel, from his pea experiments.

2. (c) — the F₂ phenotypes are 3 dominant : 1 recessive.

3. (b) — TT, Tt, Tt are tall and tt is dwarf, so 3 : 1.

4. (b) — female XX, male XY.

5. (b) — the mother gives only X; the father gives X or Y.

6. (a) — trisomy 21, so 47 chromosomes.

7. (c) — a male has one X, so a single recessive gene shows; a female needs two.

2.5 Physiological Structure and Life Process

Facts. The brain and spinal cord form the central nervous system. A reflex action is rapid and involuntary, and passes through the spinal cord. Insulin from the pancreas lowers blood sugar. The human heart has four chambers. The nephron is the functional unit of the kidney. Blood group O is the universal donor, AB the universal recipient.

1. The functional unit of the nervous system is the [1]anephronbneuroncalveolusdvillus
2. The hormone that lowers the blood sugar level is [1]aglucagonbadrenalinecinsulindthyroxine
3. The chamber of the heart that pumps oxygenated blood to the body is the [1]aright atriumbleft atriumcright ventricledleft ventricle
4. A reflex action is controlled by the [1]acerebrumbspinal cordccerebellumdpituitary
5. The functional unit of the kidney is the [1]aneuronbnephroncureterdbladder
6. The universal blood donor group is [1]aABbAcBdO
7. Fertilisation in humans normally takes place in the [1]auterusbovarycfallopian tubedvagina

Answers

1. (b) — a neuron carries nerve impulses; the nephron belongs to the kidney.

2. (c) — insulin from the pancreas; glucagon raises sugar.

3. (d) — the left ventricle drives blood through the aorta to the body.

4. (b) — the reflex arc passes through the spinal cord, bypassing thinking.

5. (b) — each kidney has about a million nephrons.

6. (d) — group O red cells carry no A or B antigens.

7. (c) — the ovum meets the sperm in the fallopian tube, then travels to the uterus.

2.6 Nature and Environment

Facts. Greenhouse gases: carbon dioxide, methane, nitrous oxide, water vapour, CFCs. Chlorofluorocarbons deplete the ozone layer. Acid rain has pH below 5.6 and is caused mainly by sulphur dioxide and oxides of nitrogen. The 3R principle is reduce, reuse, recycle.

1. The gas mainly responsible for global warming is [1]aoxygenbnitrogenccarbon dioxidedargon
2. The ozone layer is mainly damaged by [1]aCFCsbmethane onlycoxygendhelium
3. Acid rain forms when rain water dissolves [1]aCO and N₂bSO₂ and NOₓcO₂ and H₂dAr and Ne
4. Which is a biodegradable waste? [1]aplastic bagbglass bottlecvegetable peeldaluminium can
5. In a food chain, the producer is [1]aa deerbgreen grassca tigerda fungus
6. Which of these is NOT part of the 3R principle? [1]areducebreusecrecycledrefuse to recycle
7. Chitwan National Park is mainly protected to conserve [1]asnow leopard in the high Himalayabone-horned rhinoceros and tigercyakdmusk deer only

Answers

1. (c) — CO₂ is the most abundant added greenhouse gas.

2. (a) — chlorine released from CFCs breaks down ozone.

3. (b) — SO₂ and NOₓ form sulphuric and nitric acids in rain.

4. (c) — vegetable waste decays by microbes; the others do not.

5. (b) — producers make food by photosynthesis.

6. (d) — the principle is reduce, reuse, recycle.

7. (b) — Chitwan is known for the one-horned rhinoceros and the Bengal tiger.

2.7 Motion and Force

Facts. F=ma; momentum p=mv; weight W=mg; v=u+gt in free fall; universal law of gravitation F=\dfrac{Gm_1m_2}{d^2}; G=6.67\times10^{-11}\ \text{N m}^2\text{kg}^{-2}.

1. A force of 20 N acts on a 5 kg body. Its acceleration is [1]a100 m s⁻²b15 m s⁻²c4 m s⁻²d0.25 m s⁻²
2. The momentum of a 3 kg body moving at 4 m s⁻¹ is [1]a7 kg m s⁻¹b12 kg m s⁻¹c0.75 kg m s⁻¹d1.33 kg m s⁻¹
3. Which law explains why a passenger jerks forward when a bus stops suddenly? [1]aNewton's first lawbNewton's second lawcNewton's third lawdBoyle's law
4. With g=10\ \text{m s}^{-2}, the weight of a 6 kg object is [1]a0.6 Nb6 Nc16 Nd60 N
5. A stone is dropped from rest. With g=10\ \text{m s}^{-2}, its speed after 3 s is [1]a3.3 m s⁻¹b13 m s⁻¹c30 m s⁻¹d90 m s⁻¹
6. If the distance between two masses is doubled, the gravitational force becomes [1]ahalfbdoublecone-quarterdfour times
7. The mass of a body on the Moon compared with its mass on Earth is [1]aone-sixthbsix timescthe samedzero

Answers

1. (c) — a=F/m=20/5=4 m s⁻².

2. (b) — p=mv=3\times4=12 kg m s⁻¹.

3. (a) — inertia: the body tends to keep moving.

4. (d) — W=mg=6\times10=60 N.

5. (c) — v=gt=10\times3=30 m s⁻¹.

6. (c) — F\propto1/d^2, so 1/2^2=1/4.

7. (c) — mass does not change with place; only weight does.

2.8 Pressure

Facts. P=F/A (unit pascal, Pa = N m⁻²); liquid pressure P=h\rho g; Pascal's law: pressure applied to a confined fluid is transmitted equally in all directions; Archimedes' principle: upthrust equals the weight of fluid displaced; a body floats when its density is less than the fluid's. Atmospheric pressure at sea level is about 1.01\times10^{5} Pa.

1. A force of 500 N acts on an area of 0.25 m². The pressure is [1]a125 Pab2000 Pac500 Pad0.0005 Pa
2. The pressure at a depth of 10 m in water is (take \rho=1000\ \text{kg m}^{-3}, g=10\ \text{m s}^{-2}, ignore the atmosphere) [1]a10^{3} Pab10^{4} Pac10^{5} Pad10^{6} Pa
3. The hydraulic press works on the principle of [1]aArchimedesbPascalcBernoullidBoyle
4. A barometer is used to measure [1]atemperaturebatmospheric pressurecdensitydhumidity
5. An iron nail sinks but a huge iron ship floats because the ship [1]ahas less massbdisplaces water weighing as much as the shipcis hollow and emptydis painted
6. A sharp knife cuts better than a blunt one because the sharp edge has [1]aless area, so more pressurebmore areacmore massdless force
7. Upthrust on a fully submerged body does NOT depend on the [1]avolume of the bodybdensity of the liquidcvalue of gdmaterial of the body

Answers

1. (b) — P=500/0.25=2000 Pa.

2. (c) — P=h\rho g=10\times1000\times10=10^{5} Pa.

3. (b) — Pascal's law transmits pressure through the confined oil.

4. (b) — a barometer reads atmospheric pressure.

5. (b) — the floating ship's weight equals the weight of water it displaces.

6. (a) — for the same force, smaller area gives larger pressure.

7. (d) — upthrust =V\rho g depends on the volume, the liquid and g, not the body's material.

2.9 Heat

Facts. Q=mc\Delta T and Q=mL. Specific heat capacity of water is 4200 J kg⁻¹ °C⁻¹. Specific latent heat of fusion of ice is 3.36\times10^{5} J kg⁻¹ and of vaporisation of water is 2.26\times10^{6} J kg⁻¹. Water has maximum density at 4 °C. Conduction, convection and radiation are the three modes of heat transfer.

1. The heat needed to raise 2 kg of water by 10 °C is (take c=4200) [1]a8400 Jb42 000 Jc84 000 Jd420 000 J
2. The heat needed to melt 0.5 kg of ice at 0 °C is (take L=3.36\times10^{5} J kg⁻¹) [1]a1.68\times10^{5} Jb3.36\times10^{5} Jc6.72\times10^{5} Jd1.68\times10^{4} J
3. Heat reaches us from the Sun mainly by [1]aconductionbconvectioncradiationdall equally
4. Water has its maximum density at [1]a0 °Cb4 °Cc10 °Cd100 °C
5. Sea breeze blows from the sea to land during the day because [1]aland heats up faster than waterbwater heats up faster than landcland is colderdthe sea is hotter
6. Which material is the best conductor of heat? [1]awoodbglassccopperdplastic
7. The SI unit of specific heat capacity is [1]aJ kg⁻¹bJ °C⁻¹cJ kg⁻¹ K⁻¹dW

Answers

1. (c) — Q=2\times4200\times10=84\,000 J.

2. (a) — Q=0.5\times3.36\times10^{5}=1.68\times10^{5} J.

3. (c) — radiation travels through the vacuum of space.

4. (b) — anomalous expansion: water is densest at 4 °C.

5. (a) — warm air rises over land and cooler sea air flows in; land has a lower specific heat.

6. (c) — copper is a metal with free electrons.

7. (c) — c=Q/(m\Delta T), unit J kg⁻¹ K⁻¹.

2.10 Wave

Facts. v=f\lambda; f=1/T. Sound needs a medium and travels about 340 m s⁻¹ in air; echo distance d=vt/2. Light obeys the laws of reflection; refractive index n=\sin i/\sin r. Lens power P=1/f (f in metres, unit dioptre). Convex lens converges; concave lens diverges. Myopia is corrected by a concave lens.

1. A wave of frequency 50 Hz has wavelength 6.8 m. Its speed is [1]a0.14 m s⁻¹b56.8 m s⁻¹c340 m s⁻¹d3400 m s⁻¹
2. Sound cannot travel through [1]asteelbwatercairdvacuum
3. An echo is heard 3 s after a shout. If the speed of sound is 340 m s⁻¹, the reflecting wall is at [1]a170 mb340 mc510 md1020 m
4. The power of a convex lens of focal length 0.5 m is [1]a0.5 Db2 Dc5 Dd20 D
5. Short-sightedness (myopia) is corrected by a [1]aconvex lensbconcave lenscplane mirrordprism
6. The bending of light as it passes from air to glass is called [1]areflectionbdispersioncrefractionddiffraction
7. White light splits into seven colours in a prism because [1]aevery colour has a different speed in glassbthe prism makes colourcglass absorbs whitedlight changes frequency

Answers

1. (c) — v=f\lambda=50\times6.8=340 m s⁻¹.

2. (d) — sound is a mechanical wave and needs a medium.

3. (c) — d=vt/2=340\times3/2=510 m.

4. (b) — P=1/0.5=2 D.

5. (b) — a concave lens diverges rays so the image falls on the retina.

6. (c) — refraction is bending due to a change of speed.

7. (a) — dispersion: each colour has a different refractive index in glass.

2.11 Electricity and Magnetism

Facts. V=IR; P=VI=I^2R; energy (kWh) = power (kW) × time (h). A transformer works on electromagnetic induction: V_p/V_s=N_p/N_s. A generator converts mechanical energy to electrical energy; a motor does the opposite. Fleming's left-hand rule gives the force on a current-carrying conductor.

1. A 12 V battery drives a current through a 4 Ω resistor. The current is [1]a0.33 Ab3 Ac8 Ad48 A
2. The power of an appliance on 220 V drawing 5 A is [1]a44 Wb225 Wc1100 Wd1100 kW
3. A 2 kW heater runs for 3 hours. The energy used is [1]a1.5 kWhb5 kWhc6 kWhd12 kWh
4. A step-up transformer has [1]amore turns in the primarybmore turns in the secondarycequal turnsdno secondary coil
5. A generator works on the principle of [1]aelectromagnetic inductionbPascal's lawcrefractiondelectrolysis
6. The direction of force on a current-carrying wire in a magnetic field is found by [1]aFleming's left-hand rulebBoyle's lawcSnell's lawdArchimedes' principle
7. A transformer has 100 primary turns and 1000 secondary turns. With 220 V in, the output is [1]a22 Vb220 Vc2200 Vd22 000 V

Answers

1. (b) — I=V/R=12/4=3 A.

2. (c) — P=VI=220\times5=1100 W.

3. (c) — E=2\times3=6 kWh.

4. (b) — more secondary turns raise the voltage.

5. (a) — a coil turning in a magnetic field has an induced emf.

6. (a) — Fleming's left-hand rule gives the direction of the force.

7. (c) — V_s=220\times1000/100=2200 V.

2.12 Universe

Facts. Light year \approx9.46\times10^{12} km, a unit of distance. Sunlight takes about 500 s (8 min 20 s) to reach Earth. The Big Bang theory says the universe began from a hot, dense state about 13.8 billion years ago. The Milky Way is our galaxy. Mercury is the nearest planet to the Sun and Jupiter is the largest.

1. A light year is a unit of [1]atimebspeedcdistancedbrightness
2. Our galaxy is called the [1]aAndromedabMilky WaycSolar systemdOrion
3. The planet nearest to the Sun is [1]aVenusbEarthcMercurydMars
4. The theory that explains the origin of the universe from a hot, dense state is the [1]aBig Bang theorybHeredity theorycWave theorydKinetic theory
5. Energy in the core of the Sun is released by [1]anuclear fissionbnuclear fusioncburning of coaldchemical reaction
6. Sunlight takes 500 s to reach Earth. If light travels 3\times10^{5} km s⁻¹, the Earth–Sun distance is [1]a1.5\times10^{6} kmb1.5\times10^{8} kmc6\times10^{2} kmd1.5\times10^{10} km
7. A man-made body orbiting the Earth is called [1]aa cometban asteroidcan artificial satelliteda meteor

Answers

1. (c) — a light year is the distance light travels in a year.

2. (b) — the Milky Way contains our Sun.

3. (c) — Mercury orbits closest to the Sun.

4. (a) — the Big Bang theory.

5. (b) — hydrogen nuclei fuse to helium in the core.

6. (b) — d=ct=3\times10^{5}\times500=1.5\times10^{8} km.

7. (c) — satellites are artificial; the Moon is natural.

2.13 Information and Communication Technology

Facts. The CPU is the brain of the computer; RAM is volatile main memory; ROM is permanent. A network of networks is the internet; the web address is a URL. E-commerce is buying and selling over the internet. Cyber ethics and cyber crime are part of this chapter.

1. The brain of the computer is the [1]amonitorbCPUckeyboarddmouse
2. Which memory loses its data when power is switched off? [1]aROMbhard diskcRAMdpen drive
3. The full form of URL is [1]aUniform Resource LocatorbUniversal Radio LinkcUnited Resource ListdUniform Rule Logic
4. Buying goods through a website is called [1]ae-commercebe-mailce-learningde-voting
5. Sending false messages to steal a person's bank details is [1]ahacking onlybphishingcbrowsingddownloading
6. Which is an output device? [1]ascannerbprinterckeyboarddmicrophone
7. The worldwide network of connected computers is the [1]aintranetbLANcinternetdextranet

Answers

1. (b) — the CPU processes instructions.

2. (c) — RAM is volatile.

3. (a) — Uniform Resource Locator, the address of a web page.

4. (a) — e-commerce is trade over the internet.

5. (b) — phishing tricks users into giving private information.

6. (b) — a printer outputs information; the others are input devices.

7. (c) — the internet connects networks worldwide; a LAN is local.

2.14 Classification of Elements

Facts. The modern periodic law arranges elements by increasing atomic number. The modern table has 18 groups and 7 periods. Group 1 is the alkali metals, group 17 the halogens, group 18 the noble gases. Across a period atomic size decreases; down a group it increases. Elements in a group have the same number of valence electrons.

1. The modern periodic law states that properties of elements are a periodic function of their [1]aatomic massbatomic numbercdensitydvalency only
2. An element with electronic configuration 2, 8, 7 is in [1]agroup 7, period 2bgroup 17, period 3cgroup 7, period 7dgroup 3, period 17
3. Which group contains the noble gases? [1]agroup 1bgroup 2cgroup 17dgroup 18
4. Down a group the atomic size [1]adecreasesbincreasescstays the samedfirst decreases then increases
5. Which element is an alkali metal? [1]acalciumbsodiumcchlorinedneon
6. Atoms of elements in the same group have the same [1]anumber of shellsbatomic numbercnumber of valence electronsdmass number
7. The number of periods in the modern periodic table is [1]a3b7c8d18

Answers

1. (b) — Moseley's work led to atomic number as the basis.

2. (b) — three shells give period 3; seven valence electrons give group 17.

3. (d) — helium, neon, argon and the rest are in group 18.

4. (b) — each period down adds a shell.

5. (b) — sodium is in group 1; calcium is group 2.

6. (c) — the same valence electrons give similar properties.

7. (b) — seven horizontal rows.

2.15 Chemical Reaction

Facts. Types: combination, decomposition, displacement, double displacement. An acid turns blue litmus red and has pH below 7; a base turns red litmus blue and has pH above 7. Neutralisation: acid + base → salt + water. Rate of reaction rises with temperature, concentration, surface area and a catalyst.

1. The reaction 2H₂ + O₂ → 2H₂O is a [1]adecompositionbdisplacementccombinationddouble displacement
2. The reaction HCl + NaOH → NaCl + H₂O is called [1]aneutralisationbcombustioncdecompositiondreduction
3. The pH of a neutral solution at 25 °C is [1]a0b5c7d14
4. Which change speeds up a reaction? [1]alowering temperaturebincreasing surface areacdiluting the aciddremoving the catalyst
5. In Zn + CuSO₄ → ZnSO₄ + Cu, zinc [1]ais displacedbdisplaces coppercis a catalystdis a product only
6. Balanced form of Mg + O₂ → MgO has the coefficient of MgO as [1]a1b2c3d4
7. Lemon juice turns blue litmus [1]aredbgreencyellowdstays blue

Answers

1. (c) — two substances combine to form one.

2. (a) — acid and base give salt and water.

3. (c) — pH 7 is neutral.

4. (b) — more surface area gives more collisions.

5. (b) — zinc is more reactive than copper and displaces it.

6. (b) — 2\text{Mg}+\text{O}_2\to2\text{MgO}.

7. (a) — citric acid changes blue litmus to red.

2.16 Gases

Facts. Boyle's law: P_1V_1=P_2V_2 at constant temperature. Charles' law: V_1/T_1=V_2/T_2 at constant pressure, with T in kelvin. Hydrogen is prepared from zinc and dilute sulphuric acid and burns with a pop; oxygen from heating potassium chlorate with manganese dioxide and relights a glowing splint; carbon dioxide from marble and dilute hydrochloric acid and turns lime water milky.

1. A gas at 2 atm occupies 6 L. At constant temperature, at 4 atm it occupies [1]a3 Lb12 Lc6 Ld1.5 L
2. A gas of 6 L at 300 K is heated to 600 K at constant pressure. Its volume becomes [1]a3 Lb6 Lc12 Ld18 L
3. Which gas gives a pop sound with a burning splint? [1]aoxygenbcarbon dioxidechydrogendnitrogen
4. Lime water turns milky with [1]aO₂bH₂cCO₂dN₂
5. In the laboratory, hydrogen is prepared from [1]azinc and dilute H₂SO₄bmarble and HClcKClO₃ and MnO₂dcopper and dilute H₂SO₄
6. The temperature 27 °C in kelvin is [1]a27 Kb246 Kc300 Kd373 K
7. MnO₂ in the preparation of oxygen from KClO₃ acts as a [1]areactant consumedbcatalystcreducing agentdproduct

Answers

1. (a) — P_1V_1=P_2V_2: 2\times6=4\times V_2, so V_2=3 L.

2. (c) — V_2=V_1T_2/T_1=6\times600/300=12 L.

3. (c) — hydrogen burns explosively with a pop.

4. (c) — CO₂ forms insoluble calcium carbonate.

5. (a) — zinc displaces hydrogen from dilute acid; copper does not.

6. (c) — 27+273=300 K.

7. (b) — MnO₂ speeds the decomposition and is unchanged.

2.17 Metal and Non-metals

Facts. Reactivity series (high to low): K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Ag, Au. Rusting needs oxygen and water. Iron is extracted in the blast furnace; aluminium by electrolysis of alumina dissolved in molten cryolite. Alloys: brass (Cu + Zn), bronze (Cu + Sn). Sodium is stored under kerosene.

1. The most reactive metal in the list K, Na, Zn, Cu is [1]aKbNacZndCu
2. Rusting of iron requires [1]aoxygen onlybwater onlycoxygen and waterdnitrogen and water
3. Brass is an alloy of [1]acopper and zincbcopper and tinciron and carbondlead and tin
4. The ore from which aluminium is obtained is [1]ahaematitebbauxitecgalenadcinnabar
5. Which metal does NOT displace hydrogen from dilute acids? [1]azincbmagnesiumccopperdiron
6. Coating iron with zinc to prevent rusting is called [1]agalvanisationbelectrolysiscroastingdsmelting
7. Which non-metal is a good conductor of electricity? [1]asulphurbgraphiteciodinedphosphorus

Answers

1. (a) — potassium tops the reactivity series.

2. (c) — both are needed; iron(III) oxide forms.

3. (a) — brass is copper and zinc; bronze is copper and tin.

4. (b) — bauxite is hydrated aluminium oxide.

5. (c) — copper lies below hydrogen in the series.

6. (a) — galvanisation uses a zinc coat.

7. (b) — graphite has free electrons between its layers.

2.18 Hydrocarbon and its Compounds

Facts. Alkanes \text{C}_n\text{H}_{2n+2} (single bonds), alkenes \text{C}_n\text{H}_{2n} (a double bond), alkynes \text{C}_n\text{H}_{2n-2} (a triple bond). Successive members of a homologous series differ by CH₂. Ethanol is C₂H₅OH and acetic acid is CH₃COOH. Alcohol + carboxylic acid → ester + water.

1. The molecular formula of propane is [1]aC₃H₆bC₃H₈cC₃H₄dC₂H₆
2. Ethene belongs to the series of [1]aalkanesbalkenescalkynesdalcohols
3. The functional group of a carboxylic acid is [1]a–OHb–CHOc–COOHd–CO–
4. The difference between two successive members of a homologous series is [1]aCH₂bCH₃cC₂H₄dH₂
5. The compound present in vinegar is [1]aethanolbmethanolcacetic aciddformic acid
6. The formula of ethyne is [1]aC₂H₂bC₂H₄cC₂H₆dCH₄
7. Ethanol reacts with acetic acid to form [1]aetherban estercan alkanedsoap

Answers

1. (b) — n=3: \text{C}_3\text{H}_{2(3)+2}=\text{C}_3\text{H}_8.

2. (b) — it has the C=C double bond.

3. (c) — carboxyl group –COOH.

4. (a) — one carbon and two hydrogens.

5. (c) — vinegar is dilute acetic acid.

6. (a) — a triple bond: \text{C}_2\text{H}_{2(2)-2}=\text{C}_2\text{H}_2.

7. (b) — esterification gives ethyl ethanoate and water.

2.19 Chemicals used in Daily Life

Facts. Soap is the sodium (or potassium) salt of a fatty acid, made by saponification. Cement is made from limestone and clay, with gypsum added to slow setting. Glass is made from silica (sand), soda ash and limestone. Urea contains about 46% nitrogen. NPK fertilisers supply nitrogen, phosphorus and potassium. Polythene is a polymer of ethene.

1. Soap is made by heating oil or fat with [1]adilute acidbsodium hydroxidecwater onlydammonia
2. Gypsum is added to cement to [1]amake it set fasterbslow down its settingccolour itdmake it lighter
3. The raw materials of glass include [1]asilica, soda ash and limestonebclay and gypsumccoal and irondurea and potash
4. The most nitrogen-rich common fertiliser is [1]aureabsuperphosphatecpotashdlime
5. Polythene is a polymer of [1]amethanebethenecethanoldbenzene
6. Soap forms scum in hard water, whereas detergent [1]aalso forms scumbdoes not form scumcis acidic onlydis not a cleaner
7. A plastic that softens on heating and can be remoulded is [1]athermosettingbthermoplasticcbakelitedvulcanised rubber

Answers

1. (b) — fat plus NaOH gives soap and glycerol (saponification).

2. (b) — gypsum controls the setting time.

3. (a) — sand, soda ash and limestone are melted together.

4. (a) — urea is about 46% nitrogen.

5. (b) — polythene is made from many ethene molecules.

6. (b) — detergent calcium and magnesium salts remain soluble.

7. (b) — thermoplastics can be reshaped; bakelite is thermosetting.

Chapter summary

• Groups A and B are 19 marks (10 MCQ + 9 very short) and can be secured in about 30 minutes.
• Formulae to have ready: F=ma, p=mv, W=mg, P=F/A, P=h\rho g, Q=mc\Delta T, Q=mL, v=f\lambda, V=IR, P=VI, V_p/V_s=N_p/N_s, P_1V_1=P_2V_2, V_1/T_1=V_2/T_2.
• Constants: c_{\text{water}}=4200 J kg⁻¹ K⁻¹, L_f=3.36\times10^{5} J kg⁻¹, L_v=2.26\times10^{6} J kg⁻¹, speed of sound 340 m s⁻¹, speed of light 3\times10^{5} km s⁻¹.
• Biology facts: five kingdoms (Whittaker, 1969); bee development 16, 21, 24 days; F₂ ratios 3 : 1 and 9 : 3 : 3 : 1.
• Chemistry facts: alkane \text{C}_n\text{H}_{2n+2}; alkene \text{C}_n\text{H}_{2n}; alkyne \text{C}_n\text{H}_{2n-2}; temperature in kelvin is ^\circ\text{C}+273.
• After the key, always write down why the wrong options are wrong; that is how a misconception stops.