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 of the following is the poorest conductor of heat in comparison to other options?
[A] Silver
[B] Copper
[C] Lead
[D] Mercury
Show Answer
Correct Answer: C [ Lead ]
Notes:
Silver is best conductor of heat while among metals lead is poorest conductor of heat. Cooper and aluminum are good conductor while mercury is a poor conductor.
2. The Alkali metals are called good reducing agents. This implies that__:
[A] They easily capture electrons
[B] They are not stable at room temperature
[C] They easily lose electrons
[D] They don’t act with dilute acids
Show Answer
Correct Answer: C [They easily lose electrons ]
Notes:
Alkali metals have one electron in their valence shell and hence they easily lose or donate electron.
3. Which among the following is a Noble Gas?
[A] Nitrogen
[B] Hydrogen
[C] Oxygen
[D] Helium
Show Answer
Correct Answer: D [Helium]
Notes:
The noble gases are the chemical elements in group 18 of the periodic table. They are the most stable due to having the maximum number of valence electrons their outer shell can hold. This chemical series contains helium, neon, argon, krypton, xenon, and radon.
4. Which among the following scientists had discovered Radium?
[A] Marie and Pierre Curie
[B] Andre-Louis Debierne
[C] Kasimir Fajans
[D] Oswald Helmuth Gohring
Show Answer
Correct Answer: A [Marie and Pierre Curie]
Notes:
Radium(Ra) with atomic number 88 was discovered by Marie and Pierre Curie in 1898 as Radium Chloride. However, it was Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911.
5. 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.
6. Which of the following quantum numbers is represented by a period of the modern periodic table?
[A] Principal quantum number
[B] Azimuthal quantum number
[C] Magnetic quantum number
[D] None of the above
Show Answer
Correct Answer: A [Principal quantum number]
Notes:
The Period in the modern periodic table indicates the value of ‘n’ (principal quantum number) for the outermost or valence shell.
7. Which of the following elements is represented by [Xe] 6s1?
[A] Indium
[B] Rubidium
[C] Platinum
[D] Caesium
Show Answer
Correct Answer: D [Caesium]
Notes:
The atomic number of Caesium is 55 and Xenon is 54. The electronic configuration of Caesium can also be represented as [Xe] 6s1.
8. What is the bond angle in case of Ammonia molecule?
[A] 120°
[B] 150°
[C] 66°
[D] 107°
Show Answer
Correct Answer: D [107°]
Notes:
The bond angle in case of Ammonia molecule is 107° and the molecular geometry is trigonal pyramidal. The number of bond pairs in Ammonia is 3 and lone pair is 1.
9. Which of these catalyst is generally used in the hydrogenation of vegetable oils?
[A] Copper
[B] Iron
[C] Nickel
[D] Manganese
Show Answer
Correct Answer: C [Nickel]
Notes:
Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons. This is called as Addition reaction and is commonly used in the hydrogenation of vegetable oils using a nickel catalyst.
10. Which of the following represents Isocyanic acid?
[A] HNCO
[B] CNO
[C] HCO
[D] HNC
Show Answer
Correct Answer: A [HNCO]
Notes:
Isocyanic acid is a chemical compound with the formula HNCO. It was discovered in 1830 by Liebig and Wohler. It is a colourless substance which is volatile and poisonous. It is the simplest stable chemical compound containing carbon, hydrogen, nitrogen, and oxygen.
