SSC CGL Chemistry · Chemistry in Everyday Life
Chemicals in Food and Daily Use
Preservatives, flavours and colours in food with the chemical behind each, food tests and adulterants, and gases and chemicals used in labs, signs, hospitals and medicine.
Why this matters
Fourteen questions in the bank: 11 from the 2023 shifts and three from the 2024 shifts. Each names a use and asks the chemical, or the reverse, so the two tables are the whole page.
Concept 1 of 2: Chemistry in the kitchen
Definition
Preservatives:
- Sodium benzoate: the common preservative in sauces, dressings and drinks.
- Sulphites: stop browning in dried fruit, juice and wine.
Flavours, smells and colours:
- Benzaldehyde: almond flavour. Isoamyl acetate smells of banana.
- Garlic smells of sulphur compounds.
- Oleic acid is 55 to 80% of olive oil; lauric acid dominates coconut oil.
- Betanin colours beetroot; lycopene tomatoes, curcumin turmeric, beta carotene carrots.
Tests and methods:
- Iodine turns starch blue-black.
- Mechanical leavening: creaming fat and sugar, whipping egg whites or cream to trap air. Chemical leavening uses baking soda; biological uses yeast.
- Ice cream is adulterated with pepperonil, ethyl acetate, butyraldehyde and nitrate.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 1 · Chemistry in Everyday Life · Chemicals in Food and Daily Use
Benzoate keeps, bicarbonate raises
Concept 2 of 2: Gases and chemicals in use
Definition
Gases:
- Liquid helium (about 4 K) cools the superconducting magnets in MRI and NMR machines and at the LHC.
- Neon glows red in a discharge tube; argon glows violet-blue.
- Sulphur hexafluoride (SF6) is the most potent greenhouse gas known, used as an insulator in switchgear.
Names and medicine:
- Trichloromethane (CHCl3) is chloroform. Laughing gas is nitrous oxide; LPG is mainly propane and butane.
- Drugs are classified by pharmacological effect, drug action, chemical structure and molecular target, not by behaviour.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 2 · Chemistry in Everyday Life · Chemicals in Food and Daily Use
SF6, not hydrogen fluoride
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (2)
Watch out for (2)
- Benzoate keeps, bicarbonate raises→ Chemistry in the kitchen
- SF6, not hydrogen fluoride→ Gases and chemicals in use
Test yourself on a real paper
Sit a past SSC CGL paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.