WBCS (West Bengal) · General Science
Physics & Chemistry
15 practice questions with full step-by-step solutions — free, no sign-up.
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Physics & Chemistry — solved practice questions
8 WBCS General Science questions with step-by-step solutions. Attempt each, then reveal the answer.
- Q1easy
What is the SI unit of electric current?
- AAmpere
- BVolt
- CWatt
- DOhm
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Correct answer: (A) Ampere
Electric current is measured in amperes (A); the volt measures potential difference, the watt measures power, and the ohm measures resistance.
- Q2easy
Common table salt used in cooking is chemically known as:
- ASodium chloride
- BSodium bicarbonate
- CCalcium carbonate
- DPotassium chloride
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Correct answer: (A) Sodium chloride
Ordinary table salt is sodium chloride (NaCl). Sodium bicarbonate is baking soda, calcium carbonate is the main component of limestone, and potassium chloride is used only as a low-sodium salt substitute.
- Q3easy
Which instrument is used to measure atmospheric pressure?
- ABarometer
- BThermometer
- CHygrometer
- DAmmeter
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Correct answer: (A) Barometer
A barometer measures atmospheric pressure; a thermometer measures temperature, a hygrometer measures humidity, and an ammeter measures electric current.
- Q4easy
Which gas present in air is essential for burning (combustion)?
- AOxygen
- BNitrogen
- CCarbon dioxide
- DHydrogen
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Correct answer: (A) Oxygen
Oxygen supports combustion; nitrogen and carbon dioxide actually extinguish fire, and hydrogen is itself a fuel rather than a supporter of burning.
- Q5medium
Sound waves cannot travel through which of the following?
- AVacuum
- BWater
- CSteel
- DAir
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Correct answer: (A) Vacuum
Sound needs a material medium to propagate; a vacuum contains no particles to carry the vibrations, whereas air, water and steel all transmit sound.
- Q6medium
Which metal exists in the liquid state at ordinary room temperature?
- AMercury
- BSodium
- CBromine
- DLead
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Correct answer: (A) Mercury
Mercury is the only metal that is liquid at room temperature. Bromine is also liquid at room temperature but it is a non-metal, while sodium and lead are solid metals.
- Q7medium
A solution having a pH value of 3 is:
- AAcidic
- BNeutral
- CBasic (alkaline)
- DNeither acidic nor basic
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Correct answer: (A) Acidic
On the pH scale, values below 7 are acidic, exactly 7 is neutral, and above 7 is basic (alkaline); so a pH of 3 indicates an acidic solution.
- Q8medium
The substance commonly called 'slaked lime', used in whitewashing walls, is chemically:
- ACalcium hydroxide
- BCalcium oxide
- CCalcium carbonate
- DCalcium sulphate
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Correct answer: (A) Calcium hydroxide
Slaked lime is calcium hydroxide, Ca(OH)2, made by adding water to quicklime (calcium oxide, CaO). It absorbs carbon dioxide from air to form calcium carbonate, giving walls a hard white finish.
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