Chemistry
🔒 Log in to trackMatter and atomic structure, the periodic table and element records, acids-bases-pH and common compound names, ores and alloys, carbon compounds, fuels, polymers, industrial processes and pollution. CGL asks 1-2 direct factual questions.
One page per subtopic: detailed notes, every question type, formulas, tricks and practice sets.
Every formula on one printable page, grouped by subtopic.
4 exam-level questions worked step by step.
97 questions — untimed practice or a timed test with analysis.
Track record in the exam
Questions per shift in recent SSC CGL papers.
Test difficulty mix (97 questions)
Question patterns exams keep repeating
Taken from previous-year papers. If a pattern is marked "very common", expect to see it in your exam.
Common name and chemical formula
very common"Baking soda is chemically..." or "formula of plaster of Paris".
Baking soda = NaHCO₃, washing soda = Na₂CO₃·10H₂O, caustic soda = NaOH.
Quicklime = CaO, limestone = CaCO₃, gypsum = CaSO₄·2H₂O.
What is plaster of Paris chemically?
Gypsum is CaSO₄·2H₂O
Heating gypsum removes most of its water
What is left is CaSO₄·½H₂O, plaster of Paris
CaSO₄·½H₂O
Natural source and its acid
very common"The acid in tamarind / curd / lemon / ant sting is..."
Vinegar = acetic, lemon = citric, tamarind = tartaric, tomato = oxalic.
Curd = lactic, ant sting = formic.
Which acid is present in an ant sting?
Ants inject a stinging liquid
The liquid contains formic acid
A mild base like baking soda soothes it
Formic acid
Indicators and pH
very common"Phenolphthalein is colourless in..." or "which solution is more acidic".
Litmus turns red in acid. Phenolphthalein is colourless in acid and pink in base.
pH below 7 is acidic, 7 is neutral, above 7 is basic.
What colour does phenolphthalein show in a base?
In acid it is colourless
In base it changes colour
Remember: Pink in Base
Pink
Ore to metal, alloy to metals
very common"Bauxite is the ore of..." or "brass is an alloy of..."
Ores: bauxite = aluminium, haematite = iron, galena = lead, cinnabar = mercury.
Alloys: brass = Cu + Zn, bronze = Cu + Sn, solder = Pb + Sn.
Brass is an alloy of which metals?
Both brass and bronze contain copper
Brass has zinc with it
Bronze has tin with it (the usual wrong option)
Copper and zinc
Periodic table facts and symbols
very common"Father of the periodic table" or "symbol of sodium / gold / iron".
Mendeleev made the periodic table; Moseley fixed the modern one by atomic number.
Latin symbols: Na (natrium), K (kalium), Au (aurum), Fe (ferrum).
What is the chemical symbol of sodium?
The Latin name of sodium is natrium
Take the first two letters
That gives Na
Na
Industrial process and its product
very common"The Haber process gives..." or "CNG mainly contains..."
Haber = ammonia, Contact = sulphuric acid, Ostwald = nitric acid, Solvay = sodium carbonate.
CNG and biogas = methane.
The Solvay process is used to make which compound?
Haber gives ammonia
Contact gives sulphuric acid
Solvay gives washing soda (sodium carbonate)
Sodium carbonate
Pollutant and the harm it causes
common"Minamata disease is caused by..." or "acid rain is caused by..."
Minamata = mercury, itai-itai = cadmium (both Japan).
Bhopal 1984 = methyl isocyanate, acid rain = SO₂ and NOₓ, ozone hole = CFCs.
Minamata disease is caused by poisoning with which metal?
Minamata is a bay in Japan
Fish there were poisoned by factory waste
The poison was mercury
Mercury
Atom parts and isotopes
common"Who discovered the electron / neutron?" or "isotopes differ in..."
Electron = J.J. Thomson, proton = Goldstein, neutron = Chadwick, nucleus = Rutherford.
Atomic number = number of protons. Isotopes have the same protons but different neutrons.
Isotopes of an element differ in the number of what?
Isotopes are atoms of the same element
So their protons are equal
Their mass numbers differ, so their neutrons differ
Neutrons