Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. A high-refractive-index polymer (HRIP) is a polymer that has a refractive index greater than _?
[A] .50
[B] 1.0
[C] 1.20
[D] 1.50
Show Answer
Correct Answer: D [1.50]
Notes:
A high-refractive-index polymer is a polymer that has a refractive index greater than 1.50. Such materials are required for anti-reflective coating and photonic devices such as light emitting diodes (LEDs) and image sensors.
2. Trimethylxanthine is a chemical name of a stimulant which is found in tea and coffee. What is the popular name?
[A] Thein
[B] Caffeine
[C] Theobromine
[D] Theophylline
Show Answer
Correct Answer: B [Caffeine]
Notes:
Caffeine (1, 3, 7-trimethylxanthine) also known as ancient wonder drug is a basically a neurostimulant easily available all over the world and is used in different products like tea, coffee, analgesic adjuvant, soft drinks and many dietary supplements.
3. Normal” rainfall is slightly acidic (and a pH of 5.6 has been assigned which might be somewhere near 5 ) because of the presence of _______?
[A] Nitric Oxide
[B] Sulphuric Acid
[C] Nitric Acid
[D] Carbonic Acid
Show Answer
Correct Answer: D [Carbonic Acid]
Notes:
Normal rainfall is slightly acidic due to the presence of carbonic acid, which forms when carbon dioxide (CO2) dissolves in water. The pH of normal rainwater is typically around 5.6, making it mildly acidic. This natural acidity is a result of the CO2 in the atmosphere, which is produced by respiration, combustion, and other natural processes.
4. PAN (Peroxyacetyl nitrate) is a secondary gaseous compound found in _?
[A] Classical smog
[B] Volatile organic compound
[C] Photochemical smog
[D] Green manure
Show Answer
Correct Answer: C [ Photochemical smog]
Notes:
Third option is the correct answer
Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone.
5. Which of the following is the most common naturally occurring form in which silicon is found?
[A] Oxide
[B] Fluoride
[C] Nitride
[D] Sulphide
Show Answer
Correct Answer: A [ Oxide ]
Notes:
Silica is also known as Silicon dioxide, is the most prevalent form of naturally occurring silicon.
6. The presence of which of the following chemical elements helps to differentiate between sweet and sour crude oil?
[A] Iron
[B] Sulphur
[C] Vanadium
[D] Chromium
Show Answer
Correct Answer: B [ Sulphur ]
Notes:
Crude oil with high amount of Sulphur is termed as sour and with less Sulphur is called the sweet grade. Sour grade crude requires extra processing cost.
7. Which of the following is correct about the first ionization enthalpy of alkaline earth metals?
[A] It is higher than corresponding Group 1 metals
[B] It is lower than corresponding Group 1 metals
[C] No fix pattern exist
[D] None of the above
Show Answer
Correct Answer: A [It is higher than corresponding Group 1 metals]
Notes:
The first ionization enthalpy of these metals is higher than corresponding Group 1 metals due to the small size of these elements compared to the corresponding alkali metals. The second ionization enthalpy of these metals is lower than corresponding alkali metals.
8. If we take 1 kg of iron and let it rust, and none of the rust falls off, then the total weight will be___?
[A] Less than 1 Kg
[B] More than 1 Kg
[C] Exact 1 Kg
[D] More or Less than 1 Kg
Show Answer
Correct Answer: B [More than 1 Kg]
Notes:
If the rust stays attached to the main body or the flakes of rust that fall off are collected and weighed than the weight will increase. If you are using for example iron shavings than the chemical formula would look like this Fe(II) + O2 = FeO2 And the weight will increase by the mass of the shavings divided by the molar mass of iron times 2 times the molar mass of oxygen (in this case taking the molar mass of oxygen as a single oxygen atom not a pair). Thus, When rust forms, the mass of the iron object is increased by the mass of oxygen that has combined with some of the iron
9. Which of the following is correct about Solder?
[A] It is an alloy of lead and tin
[B] It is used for welding electrical wires together
[C] It has a low melting point
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Solder is an alloy of lead and tin (Pb and Sn). It has a low melting point and is used for welding electrical wires together.
10. Galena is an ore of which of the following metals?
[A] Tin
[B] Copper
[C] Lead
[D] Gold
Show Answer
Correct Answer: C [Lead]
Notes:
Galena is an ore of Lead. It is also known as lead glance. It is the natural mineral form of lead sulfide (PbS).
