- Why are appliances in houses joined in parallel?
- to save electricity
- to use less wire
- to keep the current equal
- so every appliance gets full voltage and all can run separately
Show answer
Answer: (D) so every appliance gets full voltage and all can run separately
In parallel every appliance has the same (230 V) potential difference and switching one off does not affect the others.
Read the full chapter in mind-map notes → - Why is chloroform kept in dark bottles?
- To stop evaporation
- To stop freezing
- To save its colour
- To stop phosgene forming in light
Show answer
Answer: (D) To stop phosgene forming in light
2CHCl₃ + O₂ → 2COCl₂ + 2HCl (in light).
Read the full chapter in mind-map notes → - How does Amoeba reproduce asexually?
- Budding
- Fission
- Fragmentation
- Spore formation
Show answer
Answer: (B) Fission
Amoeba reproduces through fission, splitting into two equal halves.
Read the full chapter in mind-map notes → - As temperature rises, the solubility of gases in water —
- increases
- decreases
- stays the same
- first rises then falls
Show answer
Answer: (B) decreases
Dissolving a gas is exothermic; on heating the gas escapes — ponds lose oxygen in summer.
Read the full chapter in mind-map notes → - Which gland is called the "master gland"?
- Thyroid
- Pituitary gland
- Pancreas
- Adrenal gland
Show answer
Answer: (B) Pituitary gland
The pituitary gland controls several other glands, which is exactly why it is called the "master gland".
Read the full chapter in mind-map notes → - The maximum kinetic energy of photoelectrons depends on —
- intensity
- frequency
- time of exposure
- size of the metal
Show answer
Answer: (B) frequency
Kmax = hν − φ — only on frequency (and the work function of the metal); intensity only raises the number of electrons.
Read the full chapter in mind-map notes → - Which germ layer builds the skin and nervous system?
- Ectoderm
- Mesoderm
- Endoderm
- None
Show answer
Answer: (A) Ectoderm
The ectoderm builds both the skin and the nervous system.
Read the full chapter in mind-map notes → - Which country's rocket launched India's first satellite, Aryabhata?
- the United States
- the Soviet Union
- France
- Japan
Show answer
Answer: (B) the Soviet Union
Aryabhata was launched on 19 April 1975 aboard a Soviet Cosmos-3M rocket.
Read the full chapter in mind-map notes → - What kind of ribosomes does a eukaryotic cell carry?
- 70S only
- 80S only
- Both 70S and 80S
- Neither
Show answer
Answer: (C) Both 70S and 80S
A eukaryotic cell carries 80S ribosomes in its cytoplasm and 70S ribosomes in its mitochondria and chloroplasts.
Read the full chapter in mind-map notes → - Which component is largest in Portland cement?
- Silica
- Lime (CaO)
- Alumina
- Gypsum
Show answer
Answer: (B) Lime (CaO)
CaO ≈ 50–60%, SiO₂ ≈ 20–25%, Al₂O₃ ≈ 5–10%.
Read the full chapter in mind-map notes →
- What should be used on burning petrol or oil?
- Water
- Soda-acid
- Foam
- Nothing
Show answer
Answer: (C) Foam
Foam forms a layer on the oil and keeps air out; water makes the oil float and spread.
Read the full chapter in mind-map notes → - Which Agni missile is an Intercontinental Ballistic Missile (ICBM)?
- Agni-II
- Agni-III
- Agni-V
- Agni-I
Show answer
Answer: (C) Agni-V
Agni-V is a solid-fuelled Intercontinental Ballistic Missile (ICBM) with a range of 5000-5500 km.
Read the full chapter in mind-map notes → - What is on the strip of a safety-match box?
- White phosphorus
- Sulphur
- KClO₃
- Red phosphorus and powdered glass
Show answer
Answer: (D) Red phosphorus and powdered glass
The head of the stick has KClO₃ + Sb₂S₃; the box has red phosphorus.
Read the full chapter in mind-map notes → - What does the ovule turn into after fertilisation?
- A fruit
- A seed
- A flower
- A leaf
Show answer
Answer: (B) A seed
After fertilisation, the ovule turns into a seed, while the whole ovary turns into a fruit.
Read the full chapter in mind-map notes → - In ballistic missile defence, what kind of strike is PAD built for?
- within the atmosphere (endo-atmospheric)
- outside the atmosphere (exo-atmospheric)
- only land attacks
- only naval attacks
Show answer
Answer: (B) outside the atmosphere (exo-atmospheric)
Prithvi Air Defence (PAD) is built to intercept incoming missiles outside the atmosphere (exo-atmospheric), while AAD works within the atmosphere.
Read the full chapter in mind-map notes → - What vehicle carries the Nag missile's land version?
- the Arjun tank
- NAMICA
- T-90 Bhishma
- BMP-2
Show answer
Answer: (B) NAMICA
The Nag missile's land version is carried by a tracked vehicle called NAMICA (Nag Missile Carrier).
Read the full chapter in mind-map notes → - According to Darwin's theory, how does evolution take place?
- through inheritance of acquired characters
- through natural selection
- through sudden mutation alone
- through artificial selection
Show answer
Answer: (B) through natural selection
Darwin showed that the environment selects, from among the variations that arise in a population, those individuals that are better suited to the surrounding conditions — this is natural selection.
Read the full chapter in mind-map notes → - Which disease comes from a vitamin D deficiency?
- Scurvy
- Rickets
- Beriberi
- Night blindness
Show answer
Answer: (B) Rickets
A shortage of vitamin D causes a calcium deficiency in bones, leading to rickets (in children) and osteomalacia (in adults).
Read the full chapter in mind-map notes → - In which medium does light travel fastest?
- water
- vacuum
- glass
- diamond
Show answer
Answer: (B) vacuum
The speed of light is highest in vacuum (3 × 10⁸ m/s); the higher the refractive index, the lower the speed.
Read the full chapter in mind-map notes → - Approximate percentage (w/v) of "20 volume" H₂O₂?
- 3%
- 6%
- 10%
- 20%
Show answer
Answer: (B) 6%
20 × 68/22.4 ≈ 60.7 g/L ≈ 6%; "10 volume" ≈ 3%.
Read the full chapter in mind-map notes →
- How is an EPROM wiped clean?
- with an electric shock
- by holding it under ultraviolet (UV) light
- with a magnet
- it cannot be erased at all
Show answer
Answer: (B) by holding it under ultraviolet (UV) light
Wiping an EPROM (Erasable Programmable ROM) requires holding it under an intense source of ultraviolet (UV) light.
Read the full chapter in mind-map notes → - Which is the correct order of increasing frequency in the electromagnetic spectrum?
- X-ray, UV, visible, radio
- gamma, X, UV, visible
- radio, microwave, infrared, visible, UV, X, gamma
- visible, radio, gamma, X
Show answer
Answer: (C) radio, microwave, infrared, visible, UV, X, gamma
Frequency is lowest for radio and highest for gamma rays; wavelength is the reverse.
Read the full chapter in mind-map notes → - Itai-itai disease is linked with?
- Mercury
- Cadmium
- Fluoride
- Nitrate
Show answer
Answer: (B) Cadmium
Cadmium makes bones brittle and painful — the Jinzu River in Japan.
Read the full chapter in mind-map notes → - Why was Golden Rice genetically modified?
- to increase protein
- to produce beta-carotene
- to resist pests
- to stay fresh longer
Show answer
Answer: (B) to produce beta-carotene
Golden Rice was engineered so its edible grain biosynthesises beta-carotene, a precursor of vitamin A.
Read the full chapter in mind-map notes → - Which generation of computers was built on integrated circuits?
- first
- second
- third
- fourth
Show answer
Answer: (C) third
The third generation (1964-71) was built on integrated circuits, while the fourth generation moved on to microprocessors.
Read the full chapter in mind-map notes → - Through what medium does the TV signal reach the home in a DTH service?
- through a ground cable
- directly from a satellite to a dish antenna
- through a mobile tower
- through a telephone line
Show answer
Answer: (B) directly from a satellite to a dish antenna
In DTH (Direct-To-Home), the signal travels straight from a satellite to the home's dish antenna and set-top box.
Read the full chapter in mind-map notes → - Which event proves that light is a transverse wave?
- interference
- diffraction
- polarisation
- reflection
Show answer
Answer: (C) polarisation
Polarisation happens only in transverse waves; interference and diffraction also happen in longitudinal waves (sound).
Read the full chapter in mind-map notes → - The charge on a body is always a whole-number multiple of 1.6 × 10⁻¹⁹ C — this is called:
- conservation of charge
- quantisation of charge
- induction
- polarisation
Show answer
Answer: (B) quantisation of charge
Charge is always q = ne, n a whole number — this is quantisation; conservation means the total charge stays constant.
Read the full chapter in mind-map notes → - What is a foreign particle that enters the body and triggers the immune system called?
- antibody
- antigen
- vaccine
- hormone
Show answer
Answer: (B) antigen
Any foreign particle, such as bacteria or a virus, that activates the immune system is called an antigen.
Read the full chapter in mind-map notes → - What does a virus need in order to stay alive?
- Only water
- A living host cell
- Sunlight
- Oxygen
Show answer
Answer: (B) A living host cell
Viruses are obligate parasites and cannot reproduce or grow without a living host cell.
Read the full chapter in mind-map notes →
- Sound goes from air into water. Which quantity does not change?
- speed
- wavelength
- all three change
- frequency
Show answer
Answer: (D) frequency
The source decides the frequency; on changing the medium the speed and wavelength change, not the frequency.
Read the full chapter in mind-map notes → - What change happens to the atomic and mass numbers in α-decay?
- Z + 1, A same
- no change
- Z − 1, A same
- Z − 2, A − 4
Show answer
Answer: (D) Z − 2, A − 4
An α-particle is a helium nucleus (2 protons, 2 neutrons), so Z falls by two and A by four.
Read the full chapter in mind-map notes → - Who discovered penicillin?
- Waksman
- Alexander Fleming
- Ehrlich
- Domagk
Show answer
Answer: (B) Alexander Fleming
In 1928 from the Penicillium fungus; Waksman gave streptomycin, Domagk the sulpha drug.
Read the full chapter in mind-map notes → - What can excessive use of nitrogenous fertilisers lead to?
- lower soil acidity
- higher soil acidity and nitrate leaching into groundwater
- only benefits for the soil
- none of these
Show answer
Answer: (B) higher soil acidity and nitrate leaching into groundwater
Excessive or inappropriate use can raise soil acidity and allow nitrate to leach down into the groundwater.
Read the full chapter in mind-map notes → - What kind of nutrition does a pitcher plant practise?
- Self-feeding
- Parasitic
- Insectivorous
- Saprophytic
Show answer
Answer: (C) Insectivorous
A pitcher plant is insectivorous, catching insects to make up for a shortage of nitrogen.
Read the full chapter in mind-map notes → - Which of these non-metals conducts electricity?
- Sulphur
- Graphite
- Phosphorus
- Iodine
Show answer
Answer: (B) Graphite
In the layers of graphite one electron of each carbon stays free, so it conducts electricity.
Read the full chapter in mind-map notes → - How much copper (63.5) is deposited when 1930 C passes through CuSO₄ solution?
- 6.35 g
- 1.27 g
- 0.635 g
- 0.3175 g
Show answer
Answer: (C) 0.635 g
1930 C = 0.02 F; Cu²⁺ needs 2 electrons → 0.01 mole = 0.635 g.
Read the full chapter in mind-map notes → - In Döbereiner’s triad Li, Na, K, the atomic weight of Na is nearly equal to —
- the sum of Li and K
- the average of Li and K
- half of K
- three times Li
Show answer
Answer: (B) the average of Li and K
(7 + 39)/2 = 23 — the middle one’s atomic weight equals the average of the first and third.
Read the full chapter in mind-map notes → - In which layer of the atmosphere is the ozone layer?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
Show answer
Answer: (B) Stratosphere
The ozone layer is at ≈ 15–35 km in the stratosphere; that is why temperature rises with height there.
Read the full chapter in mind-map notes → - By Wien’s law, as temperature rises the wavelength of the strongest radiation —
- increases
- decreases
- does not change
- becomes zero
Show answer
Answer: (B) decreases
λ_max × T = constant, so λ_max gets shorter as temperature rises — a hot body’s colour shifts from red towards blue.
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- The range of a ball thrown at 20 m/s at 45° (g = 10) is —
- 20 m
- 10 m
- 80 m
- 40 m
Show answer
Answer: (D) 40 m
R = u² sin2θ / g = 400 × sin90° / 10 = 40 m — the maximum range at this speed.
Read the full chapter in mind-map notes → - 1 newton equals how many dyne?
- 10³ dyne
- 10⁵ dyne
- 10⁷ dyne
- 10⁹ dyne
Show answer
Answer: (B) 10⁵ dyne
1 N = 1 kg × 1 m/s² = 1000 g × 100 cm/s² = 10⁵ dyne. The newton is the SI unit and the dyne the CGS unit of force.
Read the full chapter in mind-map notes → - Which is the correct relation between K and °C?
- K = °C − 273
- K = °C + 273
- K = °C × 2
- K = °C ÷ 2
Show answer
Answer: (B) K = °C + 273
The Kelvin scale starts from absolute zero (−273°C), so K = °C + 273 (exactly 273.15).
Read the full chapter in mind-map notes → - What kind of blood does the right atrium of the heart receive?
- Oxygen-rich
- Carbon dioxide-rich
- A mix of both
- Pure plasma
Show answer
Answer: (B) Carbon dioxide-rich
The right atrium receives carbon dioxide-rich blood from the rest of the body, which later gets purified in the lungs.
Read the full chapter in mind-map notes → - Chemical formula of laughing gas?
- NO
- N₂O
- NO₂
- N₂O₅
Show answer
Answer: (B) N₂O
Nitrous oxide (N₂O) — forms on heating NH₄NO₃; an anaesthetic.
Read the full chapter in mind-map notes → - Who overturned the vital force theory by making urea?
- Berzelius
- Wöhler
- Kolbe
- Kekulé
Show answer
Answer: (B) Wöhler
Wöhler heated ammonium cyanate in 1828 and got urea — NH₄CNO → NH₂CONH₂.
Read the full chapter in mind-map notes → - What was India's first interplanetary mission?
- Chandrayaan-I
- the Mars Orbiter Mission
- Aditya-L1
- Gaganyaan
Show answer
Answer: (B) the Mars Orbiter Mission
The Mars Orbiter Mission (Mangalyaan), launched in 2013, was India's first interplanetary mission.
Read the full chapter in mind-map notes → - Which compound forms in the Mond process of refining nickel?
- NiO
- NiSO₄
- NiCl₂
- Ni(CO)₄
Show answer
Answer: (D) Ni(CO)₄
Ni + 4CO → Ni(CO)₄ (volatile, ≈ 330–350 K), which breaks at ≈ 450–470 K to give pure nickel.
Read the full chapter in mind-map notes → - Which of these has the highest global warming potential (GWP)?
- CO₂
- CH₄
- N₂O
- SF₆
Show answer
Answer: (D) SF₆
SF₆ ≈ 23,500; N₂O ≈ 265, CH₄ ≈ 28, CO₂ = 1.
Read the full chapter in mind-map notes → - An aircraft wing lifts the plane by which principle?
- Pascal’s law
- Bernoulli’s principle
- Archimedes’ principle
- Hooke’s law
Show answer
Answer: (B) Bernoulli’s principle
Air flows faster over the wing, so the pressure there is lower; the higher pressure below pushes the wing up.
Read the full chapter in mind-map notes →
- The Chandrasekhar limit (≈ 1.44 solar masses) is related to —
- orbits of planets
- the size of a black hole
- the maximum mass of a white dwarf star
- the diameter of a galaxy
Show answer
Answer: (C) the maximum mass of a white dwarf star
A core heavier than this cannot stay a white dwarf and becomes a neutron star or black hole; Chandrasekhar got the 1983 Nobel for it.
Read the full chapter in mind-map notes → - From which generation of mobile technology did messages first start being sent encrypted?
- 1G
- 2G
- 3G
- 4G
Show answer
Answer: (B) 2G
Starting with 2G, mobile messages began being digitally encrypted, so that only the intended recipient could read them.
Read the full chapter in mind-map notes → - Who discovered the first evidence of Homo erectus, and where?
- Raymond Dart, in South Africa
- Eugene Dubois, in Java
- Charles Darwin, in England
- Hugo de Vries, in Holland
Show answer
Answer: (B) Eugene Dubois, in Java
Eugene Dubois discovered the first evidence of Homo erectus in Java in 1891 and named it Pithecanthropus erectus.
Read the full chapter in mind-map notes → - Which is the densest liquid?
- water
- kerosene
- glycerine
- mercury
Show answer
Answer: (D) mercury
The density of mercury is about 13,600 kg/m³ — 13.6 times that of water.
Read the full chapter in mind-map notes → - What kind of photoperiod plant is Xanthium?
- Long-day
- Short-day
- Day-neutral
- Vernalisation-dependent
Show answer
Answer: (B) Short-day
Xanthium is a short-day plant (SDP), needing light below a fixed critical duration to flower.
Read the full chapter in mind-map notes → - Cathode rays are made of which particles?
- protons
- electrons
- neutrons
- photons
Show answer
Answer: (B) electrons
Cathode rays are a stream of negatively charged electrons; their e/m came out the same for every gas and cathode.
Read the full chapter in mind-map notes → - Which of these is a chemical change?
- Melting of ice
- Milk turning into curd
- Sublimation of camphor
- Dissolving salt
Show answer
Answer: (B) Milk turning into curd
Curd contains a new substance (lactic acid) and the change does not reverse — the other three are physical changes.
Read the full chapter in mind-map notes → - Who coined the word "radioactivity"?
- Henri Becquerel
- Madame Curie
- Einstein
- Niels Bohr
Show answer
Answer: (B) Madame Curie
Radioactivity was discovered by Henri Becquerel, but the word itself was coined by Madame Curie.
Read the full chapter in mind-map notes → - Why was TDSAT established?
- to license new telecom companies
- to take over telecom dispute resolution, separating it from TRAI
- to install mobile towers
- to fix internet speeds
Show answer
Answer: (B) to take over telecom dispute resolution, separating it from TRAI
TDSAT was created through an ordinance effective 29 May 2000, to carve dispute resolution out of TRAI and hand it to a separate tribunal.
Read the full chapter in mind-map notes → - Why is nitrogen filled in chips packets?
- For taste
- To add moisture
- To add weight
- To stop rancidity (oxidation)
Show answer
Answer: (D) To stop rancidity (oxidation)
N₂ is inert; with no oxygen the fat is not oxidised (no staleness).
Read the full chapter in mind-map notes →
- What is Dolly the sheep known for?
- being the first GM organism
- being the first mammal cloned from an adult cell
- being the first transgenic plant
- none of these
Show answer
Answer: (B) being the first mammal cloned from an adult cell
Dolly the sheep was the first mammal successfully cloned from an adult cell through differentiation.
Read the full chapter in mind-map notes → - Who discovered the electron?
- Rutherford
- J. J. Thomson
- Chadwick
- Millikan
Show answer
Answer: (B) J. J. Thomson
In 1897 Thomson bent cathode rays in electric and magnetic fields and proved they are negatively charged particles (electrons); Millikan later measured the charge.
Read the full chapter in mind-map notes → - Compared with a closed pipe of the same length, the fundamental of an open pipe is —
- half
- equal
- double
- four times
Show answer
Answer: (C) double
Open pipe f = v/2L and closed pipe f = v/4L, so the open pipe’s fundamental is double.
Read the full chapter in mind-map notes → - Which cells of the retina recognise colours?
- rods
- cones
- nerve cells
- yellow cells
Show answer
Answer: (B) cones
Cone cells recognise colours in bright light; rods work in dim light.
Read the full chapter in mind-map notes → - Why do the testes sit outside the body in the scrotum?
- For protection
- They need a lower temperature
- To make hormones
- No particular reason
Show answer
Answer: (B) They need a lower temperature
Sperm production needs a temperature lower than the body’s own, which is why the testes sit outside.
Read the full chapter in mind-map notes → - What is a gymnosperm’s defining feature?
- Producing flowers
- A naked seed
- Having no roots
- Being single-celled
Show answer
Answer: (B) A naked seed
A gymnosperm’s seeds are never wrapped in a fruit, which is why they are called naked-seeded plants.
Read the full chapter in mind-map notes → - The value of γ = Cₚ/Cᵥ for a monatomic gas is —
- 1.4
- 1.33
- 1.67
- 1.29
Show answer
Answer: (C) 1.67
A monatomic gas has f = 3, so γ = 1 + 2/3 = 5/3 ≈ 1.67.
Read the full chapter in mind-map notes → - Which policy does India's nuclear doctrine commit to?
- First Use
- No First Use
- no stated policy
- defensive weapons only
Show answer
Answer: (B) No First Use
India's nuclear doctrine is built around a policy of "No First Use."
Read the full chapter in mind-map notes → - Standard EMF of the Daniell cell?
- 0.76 V
- 1.10 V
- 1.36 V
- 2.00 V
Show answer
Answer: (B) 1.10 V
E° = 0.34 − (−0.76) = 1.10 V; Zn anode, Cu cathode.
Read the full chapter in mind-map notes → - What is the correct rising order of levels of organisation?
- community → population → species → organism
- organism → species → population → community
- population → species → organism → community
- organism → community → population → species
Show answer
Answer: (B) organism → species → population → community
The correct rising order is: a single organism, then its species, then the population of that species, and finally the community formed by different populations together.
Read the full chapter in mind-map notes →
- Which bones belong to the axial skeleton?
- Arms and legs
- Skull, spine and ribs
- The shoulder girdle
- Fingers
Show answer
Answer: (B) Skull, spine and ribs
The skull, vertebral column, ribs and sternum belong to the axial skeleton, while arms and legs belong to the appendicular skeleton.
Read the full chapter in mind-map notes → - In which year was the Telecom Regulatory Authority of India (TRAI) established?
- 1992
- 1997
- 2000
- 2012
Show answer
Answer: (B) 1997
TRAI was set up on 20 February 1997 through an Act of Parliament.
Read the full chapter in mind-map notes → - Which species is mainly reared as the silkworm in sericulture?
- Apis mellifera
- Bombyx mori
- Catla catla
- Gossypium hirsutum
Show answer
Answer: (B) Bombyx mori
Sericulture mainly rears the species Bombyx mori as the silkworm for producing silk.
Read the full chapter in mind-map notes → - Which contraceptive method blocks both pregnancy and STDs 100% of the time?
- Condom
- IUD
- Abstinence
- Birth control pill
Show answer
Answer: (C) Abstinence
Abstinence is the only method that, by avoiding sexual contact entirely, fully blocks both pregnancy and sexually transmitted disease.
Read the full chapter in mind-map notes → - What is a fungus’s cell wall made of?
- Cellulose
- Chitin
- Protein
- Lipid
Show answer
Answer: (B) Chitin
A fungus’s cell wall is built from chitin, while a plant’s is built from cellulose.
Read the full chapter in mind-map notes → - The audible range of a normal human is —
- 0–20 Hz
- 20–20,000 Hz
- above 20,000 Hz
- 200–2000 Hz
Show answer
Answer: (B) 20–20,000 Hz
Below 20 Hz is infrasonic and above 20 kHz is ultrasonic.
Read the full chapter in mind-map notes → - What is the chromosome count like in cells produced by meiosis?
- Same as the mother cell
- Half (haploid)
- Double
- Zero
Show answer
Answer: (B) Half (haploid)
Cells produced by meiosis are haploid (n), while the mother cell was diploid (2n).
Read the full chapter in mind-map notes → - Oxidation state of iron in K₄[Fe(CN)₆]?
- +3
- 0
- +2
- +6
Show answer
Answer: (C) +2
4(+1) + x + 6(−1) = 0 → x = +2; +3 in K₃[Fe(CN)₆].
Read the full chapter in mind-map notes → - Which agency carried out Mission Shakti?
- ISRO
- DRDO
- NASA
- DAE
Show answer
Answer: (B) DRDO
Mission Shakti, the anti-satellite test on 27 March 2019, was carried out by DRDO.
Read the full chapter in mind-map notes → - Why is thermal pollution harmful to aquatic life?
- The water turns salty
- The water freezes
- Hot water holds less oxygen
- Light is reduced
Show answer
Answer: (C) Hot water holds less oxygen
The solubility of gases falls as temperature rises, while fish need more oxygen.
Read the full chapter in mind-map notes →
- How did the Nuclear Suppliers Group (NSG) treat India, despite India never signing the NPT?
- it never made any exception
- it relaxed its guidelines specifically for India
- it applied the same rules to every country
- it excluded India from the group entirely
Show answer
Answer: (B) it relaxed its guidelines specifically for India
The NSG relaxed its guidelines specifically for India, even without India ever signing the NPT.
Read the full chapter in mind-map notes → - An iron nail sinks in water but an iron ship floats, because —
- the ship displaces water equal to its own weight
- the iron of the ship is lighter
- sea water is warm
- the ship is painted
Show answer
Answer: (A) the ship displaces water equal to its own weight
Because of its hollow shape the ship displaces a huge amount of water, whose weight becomes equal to the ship’s weight.
Read the full chapter in mind-map notes → - Who discovered the magnetic effect of current?
- Faraday
- Oersted
- Ohm
- Ampère
Show answer
Answer: (B) Oersted
In 1820 Oersted saw a magnetic needle deflect near a current-carrying wire.
Read the full chapter in mind-map notes → - Which blood group is considered the universal donor?
- A
- B
- AB
- O
Show answer
Answer: (D) O
Blood group O carries no antigens, so it can be given to a person of any blood group.
Read the full chapter in mind-map notes → - What is the basic difference between Augmented Reality (AR) and Virtual Reality (VR)?
- they are the same thing
- AR adds things to the real world, VR builds an entirely new one
- VR is only for sound
- AR is only for gaming
Show answer
Answer: (B) AR adds things to the real world, VR builds an entirely new one
AR overlays computer-generated information onto a view of the real world, while VR fully immerses the user in an artificial environment.
Read the full chapter in mind-map notes → - Why does a pond full of water look shallower than it is?
- reflection
- diffraction
- scattering
- refraction
Show answer
Answer: (D) refraction
Rays from the bottom bend away from the normal while going from water to air, so the bottom looks raised.
Read the full chapter in mind-map notes → - Why does the He₂ molecule not form?
- Helium is very light
- Helium is radioactive
- Its bond order is zero
- Helium has no p orbital
Show answer
Answer: (C) Its bond order is zero
2 electrons in bonding σ1s and 2 in antibonding σ*1s — bond order ½(2 − 2) = 0.
Read the full chapter in mind-map notes → - What decides the sex of a human child?
- the mother's egg
- the father's sperm
- both equally
- nothing decides it
Show answer
Answer: (B) the father's sperm
The mother always contributes an X-carrying egg, while the father can contribute either an X or a Y sperm, so the sex of the child is decided by the father's sperm.
Read the full chapter in mind-map notes → - What shape has turnip and beetroot taken?
- Conical
- Napiform
- Fusiform
- A breathing root
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Answer: (B) Napiform
Turnip and beetroot roots take a napiform shape — nearly spherical and swollen.
Read the full chapter in mind-map notes → - What is the correct order of ecosystems from highest to lowest productivity?
- ocean, lake, grassland, mangrove
- mangrove, ocean, grassland, lake
- mangrove, grassland, lake, ocean
- ocean, mangrove, lake, grassland
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Answer: (C) mangrove, grassland, lake, ocean
From highest to lowest productivity: mangrove forest comes first, then grassland and lake at roughly the same level, and the open ocean comes last.
Read the full chapter in mind-map notes →
- How many orbitals are in a d subshell?
- 3
- 1
- 7
- 5
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Answer: (D) 5
For l = 2, m has 2l + 1 = 5 values — five d orbitals, up to 10 electrons.
Read the full chapter in mind-map notes → - Because of the lanthanoid contraction, which two elements are nearly equal in size?
- Ti and Zr
- Fe and Co
- Zr and Hf
- Cu and Ag
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Answer: (C) Zr and Hf
The contraction of the 14 lanthanoids before Hf makes Hf as small as Zr (≈ 160 pm).
Read the full chapter in mind-map notes → - Within what temperature range do enzymes work best?
- 0–10°C
- 35–40°C
- 60–70°C
- 90–100°C
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Answer: (B) 35–40°C
Most human enzymes have an ideal temperature range of 35–40°C.
Read the full chapter in mind-map notes → - Which of these ions is the smallest?
- O²⁻
- F⁻
- Na⁺
- Al³⁺
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Answer: (D) Al³⁺
All four are isoelectronic (10 e⁻); Al³⁺ has the most protons (13), so it is the smallest.
Read the full chapter in mind-map notes → - Why does galvanising protect iron even when scratched?
- Zinc is less reactive
- Zinc is shiny
- Zinc is more reactive and corrodes first
- Zinc absorbs water
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Answer: (C) Zinc is more reactive and corrodes first
Zinc becomes the sacrificial anode; with tinning the iron rusts fast once scratched.
Read the full chapter in mind-map notes → - Which of these levers always has a mechanical advantage less than 1?
- scissors
- tongs
- wheelbarrow
- see-saw
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Answer: (B) tongs
Tongs are a third-class lever (effort in the middle), whose effort arm is always shorter than the load arm.
Read the full chapter in mind-map notes → - Which state of matter is mainly found in the Sun and stars?
- Solid
- Plasma
- Bose–Einstein condensate
- Liquid
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Answer: (B) Plasma
At very high temperature gas atoms are ionised into plasma — the Sun and stars are in this state.
Read the full chapter in mind-map notes → - What is xylem’s main job?
- Carrying food
- Carrying water
- Making hormones
- Photosynthesis
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Answer: (B) Carrying water
Xylem carries water and minerals from the root to the leaves, while also giving mechanical support.
Read the full chapter in mind-map notes → - Which of these is a chemical change?
- Melting of ice
- Dissolving of salt
- Tearing of paper
- Milk turning into curd
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Answer: (D) Milk turning into curd
In making curd bacteria turn the lactose of milk into lactic acid — a new substance forms.
Read the full chapter in mind-map notes → - Product of the Hofmann bromamide reaction on acetamide?
- Ethylamine
- Methylamine
- Acetic acid
- Aniline
Show answer
Answer: (B) Methylamine
One carbon fewer: CH₃CONH₂ ⟶ CH₃NH₂.
Read the full chapter in mind-map notes →
GK question sets
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