All Free Everyday Science MCQs with Answers

391. Which product is obtained in the manufacture of soap from oils:

• A. Sodium chloride
• B. Sodium hydroxide
• C. Fats
• D. Glycerine

Explanation: Soap-making hydrolyses fats or oils, producing soap and glycerine. Sodium hydroxide is a reactant used in the process, not the product asked for.

392. The chemical used as a fixer in photography is__________?

• A. Sodium sulphate
• B. Borax
• C. Sodium thiosulphate
• D. Ammonium sulphate

Explanation: Sodium thiosulphate dissolves unexposed silver halides from photographic film, so it is called the photographic fixer. It is also known as hypo.

393. The group of minerals chemically containing hydrocarbons is_______?

• A. Silicate group
• B. Organic group
• C. Oxide group
• D. Hydride group

Explanation: The organic mineral group contains carbon-based compounds, including hydrocarbons. Silicates, oxides and hydrides are classified mainly by their inorganic chemical composition.

394. All of the following foods contain carbohydrates except.

• A. Rice
• B. Meat
• C. Potato
• D. Milk

Explanation: Meat contains mainly proteins and fats and normally provides negligible carbohydrate. Rice and potatoes are rich in starch, while milk contains the carbohydrate lactose.

395. Safe moisture content for the storage of cereals is?

• A. 10%
• B. 14%
• C. 16%
• D. 17%

Explanation: Cereal grains are generally considered safe for storage at about 14% moisture or below, because higher moisture encourages mould growth, insect activity and spoilage.

396. Which metal is extracted from sea water?

• A. Potassium
• B. Magnesium
• C. Aluminum
• D. None of these

Explanation: Magnesium compounds dissolved in seawater can be converted industrially into magnesium metal, commonly through precipitation and electrolysis. Potassium is also present in seawater but is not the standard answer to this extraction question.

397. Saccharine is made up of __________?

• A. Toluene
• B. Phenol
• C. Propane
• D. None of these

Explanation: Saccharin was historically synthesised from toluene through oxidation and subsequent chemical steps. It is an artificial sweetener and is not made from phenol or propane in the standard preparation described here.

398. PVC is obtained by the polymerisation of?

• A. Propane
• B. Vinyl chloride
• C. Styrene
• D. None of these

Explanation: PVC is polyvinyl chloride, formed by addition polymerisation of vinyl chloride monomers. Styrene instead forms polystyrene, a different plastic.

399. Which of the following is the major constituents of LPG?

• A. methane
• B. ethane
• C. hydrogen
• D. butane

Explanation: LPG is mainly a mixture of propane and butane, with the exact proportion varying by source and season. Since only butane among the listed choices is an LPG constituent, it is the intended answer.

400. Fisher unit is used to measure?

• A. Protein content
• B. Flour color
• C. Damaged starch
• D. Flour particle size

Explanation: The Fisher Sub-Sieve Sizer reports flour fineness by measuring the resistance of air passing through a packed flour sample. It is therefore associated with flour particle size, not protein or colour.