RRB JE Junior Engineer · General Awareness
General Science
Physics, chemistry and biology concepts at around tenth-standard level.
Eight concepts of tenth-standard general science as SSC and banking papers ask it: Newton's three laws, vitamin–disease pairs, cell organelles, the pH scale, atoms and everyday compounds, blood groups with insulin, mosquito-borne disease vectors, and the photosynthesis / Ohm / light-speed facts that sit in formula sheets. Almost nothing here computes — the product is tables and pegs.
- RRB JE Junior Engineer
- Medium level
- 8 concepts
- 228 practice questions
1Newton's three laws of motion
Newton's first law is inertia: a body stays at rest or in uniform straight-line motion unless a net external force acts. The second law links force to the rate of change of momentum; in the constant-mass form used in exams, F = ma, and the SI unit of force is the newton (N). The third law says every action has an equal and opposite reaction — forces come in pairs on two different bodies.
The examinable forks are which law names inertia, which writes F = ma, and which is the action–reaction pair. A ledger that 'identifies the law' and then restates its name is not a derivation.
Figure. Three laws, three forks: inertia (1st), F = ma / newton unit (2nd), equal-and-opposite pairs on two bodies (3rd).
| Law | Statement to lock | Exam cue |
|---|---|---|
| First | Inertia: rest or uniform motion unless net force acts | Defines inertia |
| Second | F = ma (force = rate of change of momentum) | SI unit of force = newton (N) |
| Third | Action and reaction equal and opposite | Pairs act on two bodies |
A book rests on a table. The book pushes down on the table; the table pushes up on the book with an equal force. Which law is the stem primarily testing?
- First law — because the book is at rest, so only inertia applies
- Second law — because equal forces mean zero mass
- Third law — because the two forces are an action–reaction pair on two bodies
Equal and opposite forces on the book and the table are the third-law pair. Rest alone does not make the stem a first-law question, and equal forces do not imply zero mass under the second law.
2Vitamins and deficiency diseases
Human vitamin questions almost always ask a deficiency disease, not a biochemical pathway. Vitamin C (ascorbic acid) deficiency causes scurvy; Vitamin D deficiency causes rickets; Vitamin A deficiency causes night blindness; Vitamin B1 (thiamine) deficiency causes beriberi; Vitamin K deficiency impairs clotting.
The legacy memory aid locks A–night blindness, C–scurvy, D–rickets, K–poor clotting; the notes separately lock B1–beriberi — keep both sets. Do not invent serum levels or daily allowances the source does not state.
Figure. Deficiency map: A→night blindness, B1→beriberi, C→scurvy, D→rickets (K→poor clotting completes the table).
| Vitamin | Also called / note | Deficiency disease |
|---|---|---|
| A | — | Night blindness |
| B1 | Thiamine | Beriberi |
| C | Ascorbic acid; citrus fruits | Scurvy (bleeding gums, weakness) |
| D | — | Rickets |
| K | — | Poor clotting |
A patient has bleeding gums and marked weakness after a long diet without citrus fruit. Which vitamin deficiency is the classic match, and what is the disease name?
- Vitamin A — night blindness
- Vitamin C (ascorbic acid) — scurvy
- Vitamin D — rickets
Bleeding gums and citrus absence point to ascorbic acid / Vitamin C and scurvy. Night blindness is Vitamin A; rickets is Vitamin D — neighbouring pairs, not this picture.
3Cell: mitochondria, nucleus, chloroplast
The cell is the structural and functional unit of life. Mitochondria are the powerhouse of the cell: they produce ATP through respiration. The nucleus contains DNA that carries genetic information. In plant cells, chloroplasts are the site of photosynthesis — the kitchen or food factory in the legacy kitchen-versus-power mnemonic.
Ribosomes are the protein factory. Exams test the nickname-to-organelle map more than ultrastructure. Mitochondria and chloroplasts are not interchangeable: one releases energy from food; the other builds food using light.
Figure. Nickname map: mitochondria release energy (ATP); chloroplasts build food in plants — not interchangeable. Nucleus holds DNA; ribosomes make protein.
| Organelle | Role / nickname | Key product or content |
|---|---|---|
| Mitochondria | Powerhouse of the cell | ATP (respiration) |
| Nucleus | Control centre / genetic HQ | DNA |
| Chloroplast | Kitchen / food factory (plants) | Photosynthesis; chlorophyll |
| Ribosome | Protein factory | Protein synthesis |
A stem asks for the organelle that generates most of the cell's ATP through respiration. A student answers chloroplast because plants need energy. What is wrong?
- Nothing — chloroplasts produce ATP as their main exam nickname
- The powerhouse that produces ATP by respiration is the mitochondrion; chloroplasts are the photosynthesis site
- Ribosomes produce ATP; mitochondria only store DNA
Mitochondria are the powerhouse (ATP via respiration). Chloroplasts run photosynthesis. Ribosomes make protein, not ATP, and DNA sits in the nucleus (and in organelle genomes, but that is not the exam nickname).
4pH scale: acid, neutral, base
The pH scale runs from 0 to 14. Values below 7 are acidic, 7 is neutral, and values above 7 are basic (alkaline). The legacy cue is below 7 sour (acid), above 7 soapy (base) — lemon juice is acidic; baking soda solutions are basic.
Exams ask which side of 7 a substance sits on, not a titration curve. Do not invent precise pH numbers for lemon or soda unless a source states them; the classification against 7 is the load.
Figure. pH bands against 7: below acidic (sour, e.g. lemon), at 7 neutral, above basic/alkaline (soapy, e.g. baking soda).
| pH | Class | Cue from the notes |
|---|---|---|
| Below 7 | Acidic | Sour — e.g. lemon juice |
| 7 | Neutral | Pure water (ideal) |
| Above 7 | Basic / alkaline | Soapy — e.g. baking soda |
A kitchen paste of baking soda in water feels slippery, not sour. On the 0–14 pH scale used in these papers, it is best classed as
- Acidic, because all kitchen chemicals sit below 7
- Basic, because everyday bases sit above 7 and match the soapy cue
- Exactly 7, because slippery means neutral
Above 7 is basic; the notes pair baking soda with the soapy/basic side. Sour/lemon is the acid side. Slippery is not the definition of neutral.
5Atom structure; water and salt
An atom's nucleus contains protons and neutrons; electrons orbit around the nucleus. Water is H_2O — two hydrogen atoms and one oxygen atom. Common salt is sodium chloride, NaCl.
These are formula and structure facts, not stoichiometry problems. A worked example that only expands 'H_2O means two H and one O' is a recall lookup wearing a lab coat.
Figure. Nucleus holds protons and neutrons; electrons orbit. Everyday formulas: water H2O (two H, one O) and common salt NaCl.
| Item | What to lock |
|---|---|
| Nucleus | Protons + neutrons |
| Electrons | Orbit around the nucleus |
| Water | H_2O — two H, one O |
| Common salt | NaCl — sodium chloride |
Which statement is correct for the model used in these papers?
- Electrons and protons both sit in the nucleus; water is NaCl
- The nucleus holds protons and neutrons; electrons orbit; water is H_2O and salt is NaCl
- Neutrons orbit the nucleus; salt is H_2O
Nucleus = protons + neutrons; electrons orbit; water = H_2O; salt = NaCl. The other options swap nucleus contents or swap the two formulas.
6Blood groups, Rh factor, insulin
Human blood groups are A, B, AB and O, each with an Rh factor (positive or negative). Insulin, produced by the pancreas, regulates blood sugar — the examinable endocrine fact paired with this biology block in the legacy notes.
Transfusion compatibility detail beyond the four groups plus Rh is out of scope for this topic's source. Lock the set of groups, the Rh tag, and the pancreas–insulin–blood-sugar chain.
Figure. ABO groups A, B, AB, O each carry an Rh tag. Insulin from the pancreas regulates blood sugar — the endocrine fact paired with this block.
| Topic | What to lock |
|---|---|
| ABO groups | A, B, AB, O |
| Rh factor | Positive or negative tag on each group |
| Insulin | Made in the pancreas; regulates blood sugar |
Blood sugar is running high and the exam stem asks which hormone brings it down and where it is made. The locked answer is
- Insulin from the pancreas
- Vitamin D from the skin only
- Haemoglobin from red cells, which is itself a hormone
Insulin from the pancreas regulates blood sugar. Vitamin D is a deficiency topic, not this hormone. Haemoglobin carries oxygen; it is not the sugar-regulating hormone.
7Malaria and dengue vectors
Malaria is caused by Plasmodium and is spread by the female Anopheles mosquito. Dengue is tied to the Aedes mosquito in the legacy matching trick — always match the disease to the correct mosquito genus.
The pathogen–vector split matters: Plasmodium is the pathogen; the female Anopheles is the vector. Mixing Anopheles with Aedes is the high-frequency trap.
Figure. Match disease to mosquito: malaria → female Anopheles (Plasmodium pathogen); dengue → Aedes. Swapping genera is the high-frequency trap.
| Disease | Pathogen (where stated) | Vector / carrier |
|---|---|---|
| Malaria | Plasmodium | Female Anopheles mosquito |
| Dengue | (virus — not expanded in source) | Aedes mosquito |
A stem names Plasmodium as the cause of malaria and asks what the female Anopheles is in that chain. The best description is
- The pathogen, because the disease follows its bite
- The vector, because it carries Plasmodium between hosts
- The same thing as Aedes, because all mosquitoes spread malaria
Plasmodium is the pathogen; the female Anopheles is the vector. Aedes is the dengue pairing in these notes, not a synonym for Anopheles.
8Photosynthesis, Ohm's law, light and sound
Photosynthesis in chloroplasts uses chlorophyll: 6CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2. Ohm's law is V = IR — voltage equals current times resistance; the SI unit of resistance is the ohm. Light in vacuum travels at about 3 \times 10^8 m/s; sound in air at room temperature is roughly 343 m/s.
These are named facts and one equation form. Lock V = IR with the ohm as the resistance unit, and keep the light-versus-sound speed contrast — exams swap the two magnitudes.
Figure. Three locks: photosynthesis equation in chloroplasts; Ohm's law V = IR with ohm as resistance unit; light in vacuum (~3×10⁸ m/s) vastly outruns sound in air (~343 m/s) — magnitudes not drawn to scale.
| Item | What to lock |
|---|---|
| Photosynthesis | 6CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2 in chloroplasts |
| Ohm's law | V = IR; unit of resistance = ohm |
| Speed of light (vacuum) | About 3 \times 10^8 m/s |
| Speed of sound (air, room temp.) | Roughly 343 m/s |
A question contrasts how long light and sound take to cross a long outdoor distance. Which pairing matches the orders of magnitude in the notes?
- Light about 3 \times 10^8 m/s in vacuum; sound roughly 343 m/s in air — light is vastly faster
- Sound at 3 \times 10^8 m/s; light at 343 m/s
- Both travel at 343 m/s; Ohm's law sets the difference
Light in vacuum is about 3 \times 10^8 m/s; sound in air is roughly 343 m/s. Swapping them is the trap. Ohm's law is V = IR, unrelated to these speeds.
Notes
- Newton's laws of motion: The first law defines inertia, the second law states force equals rate of change of momentum (F = ma), and the third law states every action has an equal and opposite reaction.
- Human vitamins: Vitamin C (ascorbic acid) deficiency causes scurvy, Vitamin D deficiency causes rickets, Vitamin A deficiency causes night blindness, and Vitamin B1 deficiency causes beriberi.
- Cell biology: The cell is the structural and functional unit of life; mitochondria are the 'powerhouse of the cell' producing ATP, and the nucleus contains DNA that carries genetic information.
- Chemistry basics: The pH scale ranges from 0 to 14, where values below 7 are acidic, 7 is neutral and above 7 is basic; the atom's nucleus contains protons and neutrons while electrons orbit around it.
- Human blood and diseases: Blood groups are A, B, AB and O with Rh factor; malaria is caused by Plasmodium spread by female Anopheles mosquitoes, and insulin (produced by the pancreas) regulates blood sugar.
Formulas
- Newton's second law: F = ma, where force equals mass times acceleration; the SI unit of force is the newton (N).
- Speed of light: Light travels at about 3 \times 10^8 m/s in vacuum; sound travels roughly 343 m/s in air at room temperature.
- Ohm's law: V = IR, where voltage equals current times resistance; the SI unit of resistance is the ohm.
- Photosynthesis: 6CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2, occurring in chloroplasts using chlorophyll.
- Water composition: Water is H_2O (two hydrogen atoms and one oxygen atom); common salt is sodium chloride, NaCl.
Exam traps & shortcuts
- Vitamin deficiency memory aid: 'A - night blindness, C - scurvy, D - rickets, K - poor clotting' - link each vitamin letter to its one classic disease.
- pH rule: 'below 7 sour (acid), above 7 soapy (base)' - lemon juice is acidic, baking soda is basic.
- Mitochondria = powerhouse; chloroplast = kitchen (food factory) of a plant cell - use kitchen vs power to separate them.
- Malaria = 'female Anopheles', Dengue = 'Aedes' - always match the disease to the correct mosquito genus.
Reference tables
Same pairings as the vitamin concept, kept here so the whole topic revises from one page.
| Vitamin | Deficiency |
|---|---|
| A | Night blindness |
| B1 | Beriberi |
| C | Scurvy |
| D | Rickets |
| K | Poor clotting |
Cross-cutting formula facts from the legacy sheet.
| Item | Lock |
|---|---|
| Newton II | F = ma; force unit = N |
| Ohm | V = IR; resistance unit = ohm |
| Light (vacuum) | \approx 3 \times 10^8 m/s |
| Sound (air) | \approx 343 m/s |
| Photosynthesis | 6CO_2 + 6H_2O \to C_6H_{12}O_6 + 6O_2 (light, chloroplast) |
| Water / salt | H_2O / NaCl |
Recap
Read only this the night before.
- Newton
- I inertia; II F = ma (unit N); III action–reaction on two bodies.
- Vitamins
- A night blindness; B1 beriberi; C scurvy; D rickets; K poor clotting.
- Organelles
- Mitochondria = powerhouse (ATP); nucleus = DNA; chloroplast = photosynthesis kitchen; ribosome = protein factory.
- pH
- Below 7 acid (sour/lemon); 7 neutral; above 7 base (soapy/baking soda).
- Atom / compounds
- Nucleus = protons + neutrons; electrons orbit. Water H_2O; salt NaCl.
- Blood / insulin
- Groups A, B, AB, O + Rh. Insulin from pancreas regulates blood sugar.
- Vectors
- Malaria: Plasmodium, female Anopheles. Dengue: Aedes.
- Speeds / Ohm
- Light \approx 3\times10^8 m/s; sound \approx 343 m/s; V = IR.
Practise General Science
Reading is free and needs no account. Practice, mocks and progress live in the app.
- 228 exam-style questions on this topic, with explanations
- A 6-question practice set that ends the chapter
- Timed mocks scored with the real marking scheme
- Readiness tracked per topic, kept on your device