- 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 → - 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 → - Which of Mendel's laws states that the two alleles of a parent separate into different gametes?
- Law of Dominance
- Law of Segregation
- Law of Independent Assortment
- none of these
Show answer
Answer: (B) Law of Segregation
The Law of Segregation says that when gametes form, the two alleles of a parent separate, so each gamete carries only one allele.
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 → - 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 → - What is the chief characteristic of mixed farming?
- growing cash crops and food crops together
- raising more than one crop together within a single field
- rearing animals and growing crops together
- none of these
Show answer
Answer: (C) rearing animals and growing crops together
In mixed farming, the farmer rears animals alongside growing crops — both form part of the same farming system.
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 → - 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 → - 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 → - 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 →
- 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 → - 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 → - 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 → - 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 → - 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 → - What is xylem’s main job?
- Carrying food
- Carrying water
- Making hormones
- Photosynthesis
Show answer
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 → - 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.
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 → - 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 → - 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 "colour" branch of biotechnology is linked to agriculture?
- red
- white
- green
- blue
Show answer
Answer: (C) green
Green biotechnology is the branch connected with applying biotechnology to agricultural processes.
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
Show answer
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 → - Which state of matter is the most compressible?
- solid
- gas
- liquid
- all equal
Show answer
Answer: (B) gas
Gas molecules have a lot of empty space between them, so a gas can be squeezed smaller (LPG, CNG cylinders).
Read the full chapter in mind-map notes → - Which isotope is used to test and treat thyroid diseases?
- Cobalt-60
- Iodine-131
- Carbon-14
- Sodium-24
Show answer
Answer: (B) Iodine-131
The thyroid gland absorbs iodine, so radioactive I-131 collects there and serves both testing and treatment.
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 → - 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 → - 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 → - What term covers both the role an organism plays and the physical space it occupies in its community?
- ecotone
- ecological niche
- habitat
- home range
Show answer
Answer: (B) ecological niche
An ecological niche covers both an organism's role in its community and its physical place, while a habitat refers only to the place.
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 → - 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 →
- 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 → - In which condition do we feel weightlessness?
- Lift at rest
- Lift accelerating upward
- Lift’s cable snaps
- Lift moving down at uniform speed
Show answer
Answer: (C) Lift’s cable snaps
When the cable snaps, the lift and the person both fall freely; the floor gives no reaction, so the apparent weight is zero.
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 → - 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 → - 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 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 → - 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 → - 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 → - 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 → - 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 →
- What is the acceleration at the mean position in SHM?
- maximum
- zero
- constant but not zero
- negative maximum
Show answer
Answer: (B) zero
At the mean position the displacement is zero and a = −ω²x, so the acceleration is also zero; the velocity is maximum there.
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 → - 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 → - 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 → - Which organism falls outside cell theory?
- Bacteria
- Viruses
- Fungi
- Algae
Show answer
Answer: (B) Viruses
Viruses fall outside cell theory, since they are not built like a true cell.
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 → - 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 → - 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 state of matter is mainly found in the Sun and stars?
- Solid
- Plasma
- Bose–Einstein condensate
- Liquid
Show answer
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 the typical reach of a LAN network?
- about 1 km or less
- 5-15 km
- an entire country
- the whole world
Show answer
Answer: (A) about 1 km or less
A LAN (Local Area Network) covers a small area such as a home, office or school — roughly 1 km or less.
Read the full chapter in mind-map notes →
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