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 compound is most commonly used in the Photochromic lenses?
[A] Potassium Dichromate
[B] Silver Chloride
[C] Potassium ferrate
[D] Ferric Chloride
Show Answer
Correct Answer: B [Silver Chloride]
Notes:
Photochromatic or Photochromic glass acquires a darker shade when exposed to bright light and returns to its original lighter shade in dim light. This happens because silver halides (iodide or chloride) is added to this glass
2. Consider the following:
- Cinnabar is also known as mercurblende
- The color of Cinnabar varies from dull grey to bright green
- Cinnabar is the most common source ore for refining elemental mercury
- Cinnabar is the historic source for the brilliant blue pigment termed azure
Which of the statements given above are correct?
[A] Only 1 and 3
[B] Only 2 and 4
[C] 1, 3 and 4
[D] All Four
Show Answer
Correct Answer: A [Only 1 and 3]
Notes:
Cinnabar, also known as mercurblende, is indeed the most common ore source for refining elemental mercury. However, its color range runs from scarlet to brick-red, not grey to green. It is known for providing the brilliant red or scarlet pigment known as vermilion, not a blue pigment.
3. Which among the following is the most important characteristic of Noble metals?
[A] Luster
[B] Non reactive nature
[C] Preciousness
[D] Rare availability
Show Answer
Correct Answer: B [Non reactive nature]
Notes:
Noble metals, such as gold, silver, and platinum, are primarily characterized by their non-reactive nature. This means they resist oxidation and corrosion, making them ideal for use in jewelry and electronics. Unlike base metals, noble metals do not easily form compounds with other elements, which is why they maintain their luster and appearance over time. Their rarity and preciousness are secondary characteristics, but their chemical stability is what truly defines them as noble.
4. Which among the following were not discovered by the time , Mendeleev published his periodic table?
[A] Lathanides
[B] Actinides
[C] Noble Gases
[D] Halogens
Show Answer
Correct Answer: C [Noble Gases]
Notes:
When Mendeleev published his periodic table in 1869, noble gases had not yet been discovered. The first noble gas, argon, was identified in 1894 by Lord Rayleigh and William Ramsay. In contrast, lanthanides and actinides were recognized later, but their existence was inferred from Mendeleev’s predictions. Halogens, including elements like chlorine and iodine, were known prior to Mendeleev’s work.
5. Acid rain is capable of damaging the buildings and historic monuments which are made up of rocks such as limestone and marble. Which among the following is the end product of such reaction?
[A] Quick Lime
[B] Calcium Carbonate
[C] Calcium Hydroxide
[D] Gypsum
Show Answer
Correct Answer: D [Gypsum]
Notes:
When sulfuric, and nitric acids, present in the acid rain reacts with the calcite in marble and limestone, it get dissolve and formed gypsum and washed off by the water. The rain can dissolve limestone and marble through direct contact.
6. What is the general trend for ionization enthalpies of alkali metals as we move down the group?
[A] it increases
[B] it decreases
[C] it is same for all
[D] None
Show Answer
Correct Answer: B [it decreases]
Notes:
The ionization enthalpies of the alkali metals are considerably low and decrease down the group from Li to Cs.
7. Which of the following is NOT correct about Group 14 elements?
[A] All of them are solids
[B] Melting points are much higher than those of corresponding elements of group 13
[C] Carbon is a non-metal
[D] Germanium is a metal
Show Answer
Correct Answer: D [Germanium is a metal]
Notes:
All members of group 14 are solids. Carbon and silicon are non-metals, germanium is a metalloid, whereas tin and lead are soft metals. Melting points and boiling points of group 14 elements are much higher than those of corresponding elements of group 13.
8. Which of the following is correct about Potassium carbonate?
[A] Its chemical formula is K CO3
[B] It is a salt which is white in colour
[C] It is used in the production of soap
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Potassium carbonate is a salt which is white in colour. It is used in the production of soap. Its chemical formula is K2 CO3.
9. Which of the following metal is the main constituent in Pewter alloy?
[A] Lead
[B] Zinc
[C] Tin
[D] Iron
Show Answer
Correct Answer: C [Tin]
Notes:
The term pewter covers a variety of alloys consisting primarily of tin. It is composed of 85–99% tin, mixed with copper, antimony, bismuth, silver or lead..
10. What do we call the difference between the initial mass energy and the total mass energy of the decay products in a radioactive decay?
[A] entropy
[B] disintegration energy
[C] alpha energy
[D] integration energy
Show Answer
Correct Answer: B [disintegration energy]
Notes:
The disintegration energy or the Q-value of a nuclear reaction is the difference between the initial mass energy and the total mass energy of the decay products.
