Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Which among the following is popularly called Hypo?
[A] Silver Bromide
[B] Silver nitrate
[C] Sodium thiosulphate
[D] Sodium phosphate
Show Answer
Correct Answer: C [Sodium thiosulphate ]
Notes:
Sodium thiosulfate is an important inorganic salt with several medical uses. It is also called sodium hyposulfite or ‘hypo’. It is used in several pharmaceutical preparations and also has various medical properties.
2. Which colour does cobalt oxide impart to glass?
[A] Brown
[B] Blue
[C] Red
[D] Yellow
Show Answer
Correct Answer: B [Blue]
Notes:
Cobalt Oxide is commonly used to create a distinctive blue hue in glasses and ceramics. The depth of the blue can be altered by changing the concentration of the oxide. In addition to being used for aesthetic purposes, Cobalt blue, which results from Cobalt Oxide, is also used because it absorbs certain wavelengths of light, making it useful for filtering out unwanted wavelengths.
3. What happens to water’s vapor pressure when heated?
[A] It increases
[B] It decreases
[C] It first increases then decreases
[D] No change
Show Answer
Correct Answer: A [It increases]
Notes:
Vapor pressure of water increases as its temperature rises. At 25°C, water’s vapor pressure is approximately 23.8 mmHg, while at 100°C it reaches 760 mmHg. When a liquid is heated, kinetic energy of molecules grows, allowing more to escape as vapor and thus increasing vapor pressure.
4. Charles Goodyear is known for which of the following ?
[A] Experiments on Rubber Plants
[B] Vulcanization of Rubber
[C] Invention of Radial Tyres
[D] Invention of Artificial Rubber
Show Answer
Correct Answer: B [Vulcanization of Rubber]
Notes:
Charles Goodyear, American inventor of the vulcanization process that made possible the commercial use of rubber. The Goodyear Tire and Rubber Company was posthumously named after him.
5. Which among the following makes Chile saltpetre different from saltpetre?
[A] Nitrate
[B] Sodium
[C] Magnesium
[D] Calcium
Show Answer
Correct Answer: B [Sodium]
Notes:
Chile saltpetre, or sodium nitrate (NaNO3), differs from regular saltpetre, which typically refers to potassium nitrate (KNO3). Chile saltpetre is primarily composed of sodium, while traditional saltpetre contains potassium. Historically, Chile saltpetre was extensively mined in the Atacama Desert and was crucial for fertilizer and explosives in the 19th century.
6. Ground Level Ozone is formed due to reaction between:
[A] VOCs, Oxides of Nitrogen & Sunlight
[B] VOCs, Sulphur dioxide & Sunlight
[C] Ozone, Sulphur dioxide & Oxides of Nitrogen
[D] Ozone, Oxides of Nitrogen & Sunlight
Show Answer
Correct Answer: A [VOCs, Oxides of Nitrogen & Sunlight]
Notes:
Ground Level Ozone results from photochemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.
7. Carbon monoxide poisoning is the most common type of fatal air poisoning in many parts of the world. What makes it such a fatal gas?
[A] CO dissolves in cytoplasm and functions as an inhibitor of the crucial enzymes for metabolism
[B] CO competes with Haemoglobin for Oxygen intake
[C] CO dissolves in blood Plasma and spreads toxicity
[D] CO converts into Carbon Dioxide in presence of water in Blood
Show Answer
Correct Answer: B [ CO competes with Haemoglobin for Oxygen intake]
Notes:
Carbon monoxide is colourless, odourless, and tasteless, but highly toxic because it combines with haemoglobin to produce carboxyhemoglobin, which usurps the space in haemoglobin that normally carries oxygen, but is ineffective for delivering oxygen to bodily tissues. Concentrations as low as 667 ppm may cause up to 50% of the body’s hemoglobin to convert to carboxyhemoglobin. The impact is irreversible and that is why that even after available of oxygen, the carboxyhemoglobin does not allow the Oxygen to be taken up.
8. Which of the following element has the highest first ionization enthalpy?
[A] Magnesium
[B] Strontium
[C] Beryllium
[D] Barium
Show Answer
Correct Answer: C [Beryllium]
Notes:
The alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms. Since the atomic size increases down the group, their ionization enthalpy decreases.
9. Which of the following are the uses of Calcium carbonate?
[A] as an antacid
[B] mild abrasive in tooth paste
[C] as a filler in cosmetics
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Calcium carbonate is used as a building material in the form of marble and in the manufacture of quick lime. Calcium carbonate is also used in the manufacture of high quality paper. It finds its use as an antacid, mild abrasive in tooth paste, a constituent of chewing gum, and a filler in cosmetics.
10. Hydraulic Washing:
- is used for concentration of ores
- is based on differences in magnetic properties of the ore components
Which of the above is / are correct?
[A] Only 1
[B] Only 2
[C] Both 1 & 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: A [Only 1 ]
Notes:
Hydraulic Washing is a method used for concentration of ores. It is a type of gravity separation as it is based on the differences in gravities of the ore and the gangue particles.