General Science MCQs For Cadet College And Forces Entry Tests
Strengthen your General Science preparation with practice MCQs, short questions and study notes on Pak Shaheens. These resources can support revision for cadet college entrance tests, competitive exams and Pakistan Armed Forces initial tests that include General Science.
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General Science Questions And Answers For Cadet College And Forces Tests
Prepare for cadet college entrance exams and Pakistan Army, Navy and PAF initial tests with these General Science questions and answers. Explore physics, chemistry, biology, the human body, Earth, astronomy and computer fundamentals.
Try answering each question before opening its answer. Use these revision questions alongside your textbooks, MCQ practice and the syllabus for your chosen examination.
283 Revision Questions · 7 Topics. Select any question to reveal its answer. Keyboard users can focus a question and press Enter. These are short-answer revision questions rather than four-option MCQ tests.
Physics And Measurements
What is the SI unit of electric charge?
The coulomb (C).
What is the wavelength range of VHF radio waves in a vacuum?
Approximately 1–10 metres, corresponding to frequencies of 30–300 MHz.
Which type of lens corrects long-sightedness?
A convex, or converging, lens corrects hyperopia.
What happens to gas pressure when volume decreases at constant temperature?
For a fixed amount of gas, pressure increases. This is Boyle’s law.
What is the approximate density of pure water near 4°C?
1 g/cm³, or 1,000 kg/m³, at approximately atmospheric pressure.
What is the SI unit of pressure?
The pascal (Pa).
What type of lens system forms an image in a camera?
A converging lens system, commonly represented by a convex lens in basic optics.
Can sound travel through a vacuum?
No. Sound needs a material medium, such as air, water or a solid.
How many colours are traditionally named in the visible spectrum?
Seven: violet, indigo, blue, green, yellow, orange and red. A prism produces a continuous spectrum rather than seven sharply separated bands.
Which instrument measures very high temperatures without direct contact?
A radiation pyrometer.
What type of waves are sound waves in air?
Longitudinal pressure waves.
Who discovered X-rays?
Wilhelm Conrad Röntgen, in 1895.
What is the speed of light in a vacuum?
Exactly 299,792,458 metres per second, approximately 300,000 kilometres per second.
What is Einstein’s mass–energy equivalence equation?
E = mc², where E is energy, m is mass and c is the speed of light in a vacuum.
What is the SI unit of electric current?
The ampere (A).
What is the SI unit of heat energy?
The joule (J).
Which units express the energy content of food?
Joules, commonly kilojoules (kJ), and kilocalories (kcal). One kilocalorie equals 4.184 kilojoules.
Which device converts alternating current into direct current?
A rectifier.
What is the number of oscillations per second called?
Frequency, measured in hertz (Hz).
How does a loudspeaker produce sound?
Its vibrating diaphragm creates pressure waves in the surrounding medium.
What are the three main methods of heat transfer?
Conduction, convection and radiation.
What is the SI unit of magnetic flux?
The weber (Wb).
Who developed the first electric battery, the voltaic pile?
Alessandro Volta, in 1800.
What happens to useful energy during real energy conversions?
Some energy becomes dispersed as heat, reducing the amount available to do useful work. Total energy is conserved.
What energy conversion occurs in a discharging battery?
Chemical energy is converted into electrical energy.
What is electric current?
The rate of flow of electric charge. In metal wires, the moving charge carriers are electrons; other materials can carry current through ions or other charge carriers.
What state is a substance normally in between its melting and boiling temperatures at fixed pressure?
The liquid state, provided the liquid phase is stable at that pressure.
How many kilograms are in one metric tonne?
1,000 kilograms.
What is a penumbra?
The partially shaded region of a shadow, observable during eclipses.
Which region of the electromagnetic spectrum generally has the shortest wavelengths?
Gamma rays in the usual school-level ordering. Gamma-ray and X-ray energy ranges can overlap.
What is common to all electromagnetic waves travelling in a vacuum?
They travel at the speed of light, c.
What is an echo?
A reflected sound heard separately from the original sound.
Which instrument measures electric current?
An ammeter.
What is the SI unit of thermodynamic temperature?
The kelvin (K).
What is the distance between successive wave crests called?
The wavelength.
Does sound generally travel faster in gases, liquids or solids?
In many common solids, followed by liquids and then gases. The actual speed depends on the material and conditions.
What is spectroscopy?
The study of how matter interacts with electromagnetic radiation, often by examining spectra.
What energy is stored when a rechargeable battery is charged?
Chemical energy is stored using electrical energy; some input energy is lost as heat.
What main energy conversion occurs in a loudspeaker?
Electrical energy is converted into sound energy through mechanical vibrations.
Where is the external magnetic field of a typical bar magnet strongest?
Near its north and south poles.
Who received the 1921 Nobel Prize in Physics for explaining the photoelectric effect?
Albert Einstein.
How many images can two ideal parallel plane mirrors facing each other form?
Theoretically infinitely many. Real mirrors show a limited number because of light loss and practical viewing conditions.
What do X-rays, visible light and radio waves have in common in a vacuum?
They travel at the same speed, c. Their wavelengths, frequencies and amplitudes need not be the same.
What is the random motion of tiny particles suspended in a fluid called?
Brownian motion, caused by collisions with the fluid’s molecules.
How does the mass of a neutron compare with that of a proton?
They are nearly equal, but a neutron is slightly more massive.
Why are very small water droplets approximately spherical?
Surface tension tends to minimize their surface area. Larger falling raindrops are distorted by airflow and are not spherical.
What does a galvanometer detect or measure?
Small electric currents.
Which electromagnetic region generally has the highest frequencies in school-level classifications?
Gamma rays.
What causes Newton’s rings?
Interference of light reflected from the surfaces of a thin film, commonly the air film between a curved lens and a flat glass plate.
Which heat-transfer mechanism allows a person to feel warmth directly from a fire?
Thermal radiation. Nearby hot air also transfers heat by convection.
Can a machine produce useful work forever without any energy input or loss?
No. A perpetual-motion machine of this kind conflicts with the laws of thermodynamics.
Why does iron feel colder than wood at the same room temperature?
Iron conducts heat away from the hand faster; wood is a much poorer thermal conductor.
Approximately how far away must a reflecting surface be for a distinct echo in air?
About 17 metres, using a minimum time gap of 0.1 seconds and a sound speed near 340 m/s. Conditions affect the result.
Which characteristic helps distinguish two voices with the same pitch and loudness?
Timbre, or sound quality, determined by the mix of frequencies and other features of the sound.
Why can a sunbeam become visible in a dusty room?
Dust particles scatter light toward the observer.
What minimum height of plane mirror lets a 6-foot-tall person see their full body?
3 feet, or half the person’s height, with the mirror positioned correctly.
What kind of waves does sonar use?
Sound waves, often ultrasonic. Radar uses radio waves; not all sonar systems operate above the audible range.
What is nuclear fusion?
A reaction in which light nuclei combine to form a heavier nucleus, releasing energy in suitable reactions.
What does a lactometer measure?
The relative density, or specific gravity, of milk. It cannot by itself prove milk purity.
Why do stars appear to twinkle?
Their light is refracted through moving layers of Earth’s atmosphere with different densities.
How can the angular magnification of a simple magnifying lens be increased?
By using a lens with a shorter focal length, for a given viewing arrangement.
What are the SI base units of length, mass and time?
The metre (m), kilogram (kg) and second (s). The litre is a unit of volume, not an SI base unit.
What is an object that produces its own light called?
A luminous object.
What kind of electromagnetic radiation does a typical electric heater emit strongly?
Infrared radiation. A sufficiently hot element may also glow visibly.
Why is the Kelvin scale called an absolute temperature scale?
It begins at absolute zero, 0 K, rather than at an arbitrary freezing point.
Which of alpha, beta and gamma radiation is not deflected by a magnetic field?
Gamma radiation, because photons have no electric charge.
Which non-flammable gas is commonly used in floating party balloons?
Helium. Hydrogen also provides lift but is flammable.
What useful energy conversion occurs in a heat engine?
Some thermal energy is converted into mechanical work, while some heat is rejected to a cooler reservoir.
What is the approximate audible frequency range for a young person with healthy hearing?
20 Hz to 20,000 Hz (20 kHz). The upper limit often decreases with age.
How large is a nanometre?
One billionth of a metre, or 10⁻⁹ m. It is useful for expressing wavelengths, but is not the smallest possible unit of length.
Which unit is commonly used to bill electrical energy?
The kilowatt-hour (kWh), equal to 3.6 million joules. It measures energy, not power.
What is measured in newtons?
Force. The newton (N) is its SI unit.
Who designed the successful Rover safety bicycle in 1885?
John Kemp Starley. Bicycle development involved many inventors.
What type of energy does moving air possess?
Kinetic energy.
Does a photodiode convert a television signal into visible light?
No. A photodiode detects light and converts it into an electrical signal. Television screens produce images using display technologies such as LCDs with backlights or OLEDs.
How many spark plugs are used for ignition in a conventional diesel engine?
None. Diesel engines use compression ignition; some use glow plugs to assist cold starting.
Which electromagnetic radiation is used in thermal night-vision imaging?
Infrared radiation. Other night-vision systems amplify low levels of visible and near-infrared light.
At approximately what temperature does pure water reach its maximum density at atmospheric pressure?
4°C, more precisely about 3.98°C.
What does a Geiger–Müller counter detect?
Ionizing radiation. Sensitivity to alpha, beta, gamma or X-rays depends on the instrument and its window design.
Which electronic devices replaced vacuum tubes in many circuits?
Transistors, later incorporated into integrated circuits. Vacuum tubes still have some specialist uses.
Chemistry And Matter
Who discovered natural radioactivity?
Henri Becquerel, in 1896.
Which naturally occurring element is generally considered the densest at standard conditions?
Osmium; its density is very close to that of iridium.
What does CNG stand for?
Compressed natural gas.
What is oxidation in terms of electrons?
Loss of electrons.
Diamond is an allotrope of which element?
Carbon.
Which gas is commonly called laughing gas?
Nitrous oxide (N₂O).
Which state of matter consists of ionized gas?
Plasma, often called the fourth state of matter.
Which metals are the main components of traditional bronze?
Copper and tin.
Who discovered the neutron?
James Chadwick, in 1932.
Who established the existence of the atomic nucleus?
Ernest Rutherford, based on the interpretation of alpha-particle scattering experiments.
Who discovered the electron?
J. J. Thomson, in 1897.
Is an anode always positive?
No. Oxidation occurs at the anode. It is positive in an electrolytic cell and negative in a discharging galvanic cell.
What are the horizontal rows of the periodic table called?
Periods.
What are the vertical columns of the periodic table called?
Groups.
Which metallic element is liquid at ordinary room temperature?
Mercury.
Which non-metallic element is liquid at ordinary room temperature?
Bromine.
What can form when a gas becomes sufficiently ionized?
Plasma.
What is the chemical symbol for gold?
Au.
What material is heated to make plaster of Paris?
Gypsum. Partial dehydration produces calcium sulfate hemihydrate.
Is helium chemically toxic?
Helium is chemically inert and non-toxic, but it can displace oxygen and cause asphyxiation.
Can ordinary chemical reactions turn copper into gold?
No. Changing one element into another requires nuclear transmutation, not a chemical reaction, and is not a practical way to produce gold.
Which metals make up German silver, also called nickel silver?
Copper, nickel and zinc. Despite its name, it normally contains no silver.
What is the change from gas to liquid called?
Condensation.
What is vinegar?
An aqueous solution containing acetic acid, also called ethanoic acid; it is a mixture, not a pure chemical.
A radioactive sample has a half-life of 8 days. How long does 10 mg take to fall to 5 mg?
8 days, because this is one half-life.
How can the electron count of a neutral atom be determined?
It equals the atomic number, which is also the number of protons.
What is matter?
Anything that has mass and occupies space.
What are the basic chemical building blocks of ordinary matter?
Atoms, which contain subatomic particles.
What is the central region of an atom containing protons and usually neutrons called?
The nucleus. The most common hydrogen nucleus contains one proton and no neutron.
Human Body And Nutrition
What is the average lifespan of a human red blood cell?
About 120 days.
How much blood does an average adult have?
Approximately 5 litres; the amount varies with body size and other factors.
Is the volume of air a person breathes each day fixed?
No. It varies with breathing rate, breath size and activity. At 6 litres per minute, the total is approximately 8,640 litres per day.
Do all white blood cells have the same lifespan?
No. Lifespans vary by cell type, from hours or days to years for some long-lived immune cells.
What is the liquid component of blood called?
Plasma.
Which organs produce urine?
The kidneys.
Which organs filter blood to remove wastes and excess water as urine?
The kidneys.
What does a glucose biosensor measure?
Glucose concentration, such as blood glucose. Other biosensors detect different substances.
Which fluoride-containing compounds help protect teeth against decay?
Fluorides strengthen enamel and help prevent tooth decay. Elemental fluorine is not used for this purpose.
What is a commonly quoted average normal human body temperature?
About 37°C (98.6°F). Normal values vary with the person, time and measurement site.
Why is “the weakest bone” an unclear question?
Bone strength depends on size, structure, loading and the individual. The clavicle is commonly fractured, but it is not a universally defined weakest bone.
Which is the longest and strongest bone in the human body?
The femur, or thigh bone.
What is the hardest substance in the human body?
Tooth enamel, which is not bone.
Which element is most abundant in the human body by mass?
Oxygen.
What does systole mean?
The contraction phase of the heart, especially the ventricles.
What are the two main transparent substances filling the eye’s interior?
Aqueous humour, a watery fluid, and vitreous humour, a gel-like substance.
Where is the femur located?
In the thigh.
How many bones make up the adult skull, excluding ear ossicles and the hyoid?
22 bones: 8 cranial bones and 14 facial bones.
How many bones are usually counted in an adult human skeleton?
206; anatomical variation can occur.
Which blood group is the universal red-cell donor in the ABO/Rh system?
O negative. Actual transfusions still require appropriate testing and matching.
Which large organ excretes small amounts of water, salts and urea through sweat?
The skin. The kidneys are the main organs for eliminating nitrogenous wastes.
What bony structure encloses the brain?
The cranium.
Which two bones form the human forearm?
The radius and ulna.
Which organ produces bile?
The liver. The gallbladder stores and concentrates bile, then releases it into the small intestine.
What are major functions of the human skeleton?
Support, protection, movement, mineral storage and blood-cell formation in bone marrow. Protein synthesis itself is performed by cellular machinery such as ribosomes.
Which major nutrient are pulses particularly valued for?
Protein; pulses also provide fibre and other nutrients.
What can abnormal lipid accumulation in nerve cells cause in lipid-storage disorders?
Progressive neurological damage; the effects depend on the specific disorder. It is not a single diagnosis.
Which bone is commonly called the collarbone or “beauty bone”?
The clavicle, in both males and females.
Why does rigor mortis eventually disappear?
Post-mortem breakdown of muscle proteins releases the stiffness. Rigor initially develops because ATP depletion prevents actin–myosin cross-bridges from detaching normally.
What is the release of an egg from an ovary called?
Ovulation.
What cushions the developing fetus against mechanical shocks?
Amniotic fluid within the amniotic sac.
Which sugar in seminal fluid provides an energy source for sperm?
Fructose, supplied mainly by the seminal vesicles.
Who first described sickle-shaped red blood cells in a 1910 medical report?
James B. Herrick. Vernon Ingram later identified the amino-acid substitution in sickle-cell haemoglobin.
What is assimilation in nutrition?
The use of absorbed nutrients by cells for energy, growth, repair and the synthesis of body substances.
Which lung disease involving damaged alveoli is strongly linked to smoking?
Emphysema, a form of chronic obstructive pulmonary disease. Smoking also causes other respiratory illnesses.
What is the normal pH range of human arterial blood?
Approximately 7.35–7.45, with an average near 7.4.
How can atherosclerosis contribute to a heart attack?
Plaque buildup and plaque rupture in coronary arteries can reduce or block blood flow to heart muscle.
How do villi and microvilli help the small intestine?
They increase the surface area available for nutrient absorption.
What is glycolysis?
A pathway that breaks one glucose molecule into two pyruvate molecules, producing a net gain of ATP and NADH.
How does a body’s temperature change after death?
It generally moves toward the surrounding temperature over time; the rate depends on the environment and other conditions.
Deficiency of which vitamin can cause night blindness?
Vitamin A.
What causes dental caries, or tooth decay?
Acids made by plaque bacteria as they metabolize sugars damage tooth enamel.
Where does digestion begin?
In the mouth, with chewing and the action of saliva.
Where are most blood cells produced in a healthy adult?
In red bone marrow.
What is a common resting heart-rate range for adults?
About 60–100 beats per minute; some healthy trained people have lower rates. A value near 72 is an example, not a universal constant.
To which visible wavelength is normal human daylight vision most sensitive?
Approximately 555 nanometres, in the yellow-green region. Sensitivity shifts under dim-light conditions.
Is the fat content of buffalo milk always 10%?
No. It varies with breed, diet and other conditions; values around 6–8% are common, with higher and lower values possible.
Which sugar is usually most abundant in honey?
Fructose, followed by glucose; proportions vary with the floral source.
What can severe vitamin D deficiency cause in children?
Rickets, in which growing bones do not mineralize properly. In adults it can cause osteomalacia.
Where is most chemical digestion completed?
In the small intestine.
Which blood group is the universal red-cell recipient in the ABO/Rh system?
AB positive. Clinical transfusions still need appropriate testing and compatibility checks.
Which common salt is present in sweat?
Sodium chloride.
Where are most digested nutrients absorbed in humans?
In the small intestine.
Where is the tibia found?
In the lower leg; it is commonly called the shinbone.
What is the main mineral component of bones and teeth?
Hydroxyapatite, a crystalline calcium phosphate. Bones also contain an organic matrix rich in collagen.
Which gland is traditionally called the master gland?
The pituitary gland, because it regulates several other endocrine glands. It is itself controlled largely by the hypothalamus.
Which metal is present in the haem group of haemoglobin?
Iron. Haemoglobin is a protein containing iron-bearing haem groups, not mainly iron by mass.
What is the largest organ of the human body?
The skin.
The medulla oblongata belongs to which part of the nervous system?
The brainstem, within the brain.
Which muscle type is mainly controlled by the somatic rather than the autonomic nervous system?
Skeletal muscle. The autonomic system mainly regulates smooth muscle, cardiac muscle and glands.
Biology And Plant Science
Which snake is widely known for rapid movement on land?
The black mamba. Reported speed rankings vary with measurement conditions.
What is a herbivore? Give an example.
An animal that mainly eats plants; a cow is an example.
Which plant tissue transports water and dissolved minerals?
Xylem.
What are organisms that make their own organic food called?
Autotrophs. In food chains, they function as producers.
Are bacteria prokaryotes or eukaryotes?
Prokaryotes; they lack a membrane-bound nucleus.
Who proposed the DNA double-helix model in 1953?
James Watson and Francis Crick, drawing on crucial experimental work by Rosalind Franklin, Maurice Wilkins and others.
What is pollination?
The transfer of pollen from an anther to a stigma in flowering plants.
What is the movement of a substance against its concentration gradient using energy called?
Active transport.
Which root structures absorb much of a plant’s water and minerals?
Root hairs increase the surface area for absorption.
Which marine mammals are known for complex learning and social behaviour?
Dolphins.
Which type of nuclear division usually supports growth and repair in eukaryotes?
Mitosis. Meiosis produces haploid cells for sexual reproduction, and most bacteria divide by binary fission.
What are plants adapted to dry habitats called?
Xerophytes.
What is the simplest amino acid found in proteins?
Glycine.
Which organelle contains most genetic material and regulates many activities in a eukaryotic cell?
The nucleus. Mature human red blood cells are an important exception because they lack a nucleus.
What forms the internal framework of typical motile eukaryotic flagella?
Microtubules, usually in a 9 + 2 arrangement. Bacterial flagella have a different structure and are largely made of flagellin.
Who crystallized tobacco mosaic virus in 1935?
Wendell M. Stanley.
What is a virion?
A complete virus particle outside a host cell. Virions may be enveloped or non-enveloped.
What colour do Gram-positive bacteria retain after Gram staining?
Purple or violet, because they retain the crystal violet–iodine complex after decolorization.
Which stage of the malaria parasite is transmitted to humans by an infected mosquito?
Sporozoites, transmitted by an infected female Anopheles mosquito.
Who introduced the terms prokaryote and eukaryote?
Édouard Chatton.
How do many fungi reproduce asexually?
By forming asexual spores; some also reproduce by budding or fragmentation.
Which root-like structures anchor Marchantia to its substrate?
Rhizoids.
What are vascular plants also called?
Tracheophytes.
What causes influenza?
Influenza viruses.
Which major body regions are found in a typical adult insect?
The head, thorax and abdomen. Not all arthropods have these three distinct regions.
How does an amoeba move and engulf food?
By extending pseudopodia, or “false feet.”
What does the inner tissue layer of a cnidarian form?
The gastrodermis, which lines the gastrovascular cavity and helps with digestion.
What are seed-producing vascular plants called?
Spermatophytes, including gymnosperms and angiosperms. Not all vascular plants produce seeds.
Which non-vascular land plants lack seeds?
Bryophytes, including mosses, liverworts and hornworts.
What is a kangaroo’s pouch called?
A marsupium. An animal belonging to the group is called a marsupial.
In which animals are parabronchi part of the lungs?
Birds.
What is the reference water potential of pure water at atmospheric pressure?
Zero, under the standard reference conditions used in plant physiology.
Which cells control the opening and closing of stomata?
Guard cells, which are kidney-shaped in many plants and dumbbell-shaped in grasses.
What is plasmolysis?
The shrinking of a plant cell’s protoplast away from the cell wall after water loss in a hypertonic solution.
What is winter dormancy in reptiles commonly called?
Brumation. It is similar to, but physiologically distinct from, mammalian hibernation.
Which plants are commonly called horsetails or sphenopsids?
Plants of the genus Equisetum and their related fossil groups.
What do N, P and K stand for in plant fertilizers?
Nitrogen, phosphorus and potassium, three major plant nutrients.
Which biotechnology process is used to make foods such as yoghurt and bread?
Fermentation, using microorganisms or their enzymes.
Which is the largest living species of cat?
The tiger.
Which sex is heterogametic in domestic chickens?
Females, which have ZW sex chromosomes; males are ZZ.
Earth And Environment
Which element is most abundant in Earth’s crust by mass?
Oxygen.
Does seawater freeze at a higher or lower temperature than fresh water?
Lower. Typical seawater freezes at about −1.9°C because dissolved salts lower its freezing point.
Approximately what proportion of dry air is carbon dioxide?
About 0.04% by volume. The concentration varies and is increasing over time; it is not 3%.
Approximately how much of Earth’s surface is covered by water?
71%.
What are Earth’s three main compositional layers?
The crust, mantle and core. A mechanical classification commonly distinguishes five layers instead.
On which outer solid layer of Earth do we live?
The crust.
Which of Earth’s main layers is the thickest?
The mantle.
Approximately how thick is Earth’s crust?
About 5–70 kilometres, depending on location; continental crust is generally thicker than oceanic crust.
Which international reference line passes near New Zealand in the Pacific?
The International Date Line.
What is the estimated temperature near Earth’s centre?
Roughly 5,000–6,000°C; it is an estimate rather than a direct measurement.
What is a seasonally reversing wind system called?
A monsoon.
What is the approximate average depth of the world ocean?
About 3.7 kilometres.
What causes air to move as wind?
Differences in atmospheric pressure drive air movement; Earth’s rotation and friction also affect the wind.
Which instrument measures wind speed?
An anemometer.
What is radiocarbon dating used to date?
Once-living organic material, generally up to about 50,000 years old. It cannot directly date every fossil or rock.
What does seismology study?
Earthquakes and seismic waves.
Which instrument measures atmospheric pressure?
A barometer.
How does energy from the Sun reach Earth through space?
By electromagnetic radiation, also called solar radiation.
Which atmospheric layer is nearest to Earth’s surface?
The troposphere.
Which continent contains the geographic South Pole?
Antarctica.
Where is the deepest known point in the ocean?
Challenger Deep in the Mariana Trench, in the western Pacific Ocean.
What causes sunlight to scatter in Earth’s atmosphere?
Air molecules and suspended particles. Molecular Rayleigh scattering is a major reason the daytime sky looks blue.
What is the study of Earth’s chemical composition called?
Geochemistry.
Is there one electricity source that is always the cheapest everywhere?
No. Costs depend on location, financing, fuel, storage and grid needs. Solar and onshore wind can be very low-cost options under suitable conditions.
Which fossil-fuel pollutants contribute to acid rain?
Sulfur dioxide and nitrogen oxides, which react in the atmosphere to form acids.
What does the Richter scale describe?
Earthquake magnitude, rather than the intensity of shaking at a particular location. Moment magnitude is now widely used for larger earthquakes.
Name an African country crossed by the equator.
Kenya. Other examples include Uganda and the Democratic Republic of the Congo.
Which instrument measures humidity?
A hygrometer.
Are all sedimentary rocks highly porous?
No. Porosity varies widely with rock type, grain arrangement, cementation and compaction.
With which environment is an oasis associated?
A desert; an oasis is a place where water supports vegetation.
How deep is the ocean’s main sunlight, or euphotic, zone?
Roughly the upper 200 metres, depending on water clarity. Much weaker sunlight can reach deeper under suitable conditions.
Space And Astronomy
Which is the outermost planet in our solar system?
Neptune is the outermost of the eight recognized planets.
What type of celestial object is the Sun?
A star.
Which element is most abundant in the universe?
Hydrogen.
Which planet can approach Earth most closely?
Venus. The planet with the smallest distance from Earth at a particular time changes; “closest on average” is a different question.
Which planet has the highest average orbital speed around the Sun?
Mercury.
What shape are the orbits of many periodic comets?
Highly elongated ellipses. Not every comet follows a bound elliptical orbit.
Which planet is brightest as seen from Earth?
Venus, when visible.
Approximately how old is the universe?
13.8 billion years.
Which planet is nearest to the Sun?
Mercury.
How does the Sun’s diameter compare with the Moon’s diameter?
The Sun’s diameter is about 400 times greater. It is also about 400 times farther from Earth, so their apparent sizes are similar.
Whose 1929 observations helped establish the relationship between galaxy distance and recession speed?
Edwin Hubble’s observations helped establish this relationship, now called the Hubble–Lemaître law.
What process produces most of the Sun’s energy?
Nuclear fusion, mainly converting hydrogen into helium in the core.
Which regular movement of ocean water is strongly influenced by the Moon’s gravity?
Tides. The Sun also contributes to tides.
What is a meteor?
The streak of light produced when a meteoroid enters an atmosphere and heats the surrounding gas; a surviving fragment reaching the ground is a meteorite.
What is a constellation?
A recognized region of the sky associated with a traditional pattern of stars. The stars need not be physically close together.
Why does the sky look black to an astronaut outside Earth’s atmosphere?
There is too little surrounding gas to scatter sunlight across the sky as the atmosphere does on Earth.
What is a light-year?
A unit of distance: the distance light travels in a vacuum in one year, about 9.46 trillion kilometres.
What does a parsec measure?
Distance. One parsec is approximately 3.26 light-years.
What is the mean distance between Earth and the Sun?
Approximately 149.6 million kilometres, or one astronomical unit (AU).
What is the visible surface layer of the Sun called?
The photosphere. The Sun has no solid surface, and its atmosphere extends above this layer.
Which planet has the largest number of confirmed moons in NASA’s published listings used for this edition?
Saturn. Confirmed moon counts change as discoveries are verified, so consult NASA’s current listings for updates.
What are asteroids?
Small rocky or metallic bodies orbiting the Sun; many are found in the belt between Mars and Jupiter.
What is the approximate temperature of the Sun’s core?
About 15 million kelvin; at this scale, the numerical value in degrees Celsius is nearly the same.
What causes the phases of the Moon?
As the Moon orbits Earth, we see different portions of its sunlit half. Ordinary phases are not caused by Earth’s shadow.
What are the zodiac constellations?
Constellations along the ecliptic, the Sun’s apparent annual path across the sky. The Moon and planets appear near this path.
What is the altitude of a geostationary satellite above Earth’s equator?
Approximately 35,786 kilometres.
How does a moving clock behave according to special relativity?
Relative to an inertial observer, a moving clock ticks more slowly. This effect becomes substantial at speeds approaching the speed of light.
How many natural moons does Mars have?
Two: Phobos and Deimos.
Can astronomers receive the Nobel Prize in Physics?
Yes. For example, Michel Mayor and Didier Queloz shared the 2019 prize for discovering an exoplanet orbiting a solar-type star.
How long does Mercury take to orbit the Sun?
About 88 Earth days.
What is Earth’s approximate surface escape speed, ignoring air resistance?
11.2 kilometres per second, or about 7 miles per second.
Who proposed an expanding-universe model in 1927?
Georges Lemaître. Alexander Friedmann had derived expanding solutions earlier, and Hubble later supplied influential observational evidence.
Who developed special relativity in 1905?
Albert Einstein. The idea of relative motion also has earlier foundations, including Galileo’s work.
Which calendar month can occasionally contain no new moon?
February, because it can be shorter than a lunar synodic month.
Computer Fundamentals
From which Latin verb does the word “compute” derive?
Computare, meaning to calculate or reckon.
Who is commonly called the father of the computer?
Charles Babbage, known for his designs for the Difference Engine and Analytical Engine.
Who are widely called the fathers of the Internet for their work on TCP/IP?
Vint Cerf and Robert Kahn. The Internet was developed through the contributions of many people.
What is a computer system with more than one processor called?
A multiprocessor system. A multicore processor is a related but distinct arrangement.
Which component is often called the brain of a computer?
The central processing unit (CPU), which executes instructions.
What is a hybrid computer?
A system combining features of analog and digital computing.
What does ALU stand for?
Arithmetic logic unit.
What does RAM stand for?
Random access memory.
What is computer software?
Programs, instructions and related data used by a computer, as distinct from its physical hardware.
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