Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. 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.
2. 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.
3. In a photochemical smog, which gas causes irritation to mucous membrane and respiratory system?
[A] Nitrous oxide
[B] Sulphur dioxide
[C] Ozone
[D] Carbon monoxide
Show Answer
Correct Answer: C [ Ozone]
Notes:Ozone (O3) is the most common photochemical oxidant in photochemical smog. Inhaling ozone can cause irritation to the mucous membrane and respiratory system. Ozone can also cause chest constriction and damage to vegetation.
Other components of photochemical smog include:
- Nitrogen dioxide (NO2)
- Peroxyacetylnitrate (PAN)
- Aldehydes
Other air pollutants that can be harmful to humans include:
- Sulfur dioxide
- Volatile organic compounds (VOCs)
- Dioxins
- Polycyclic aromatic hydrocarbons (PAHs)
Carbon monoxide can cause hyperventilation, respiratory distress, and stillbirths. At high levels, carbon monoxide can even cause direct poisoning.
4. Which of the following is the correct order of composition of biogas released through anaerobic bio-digester system?
[A] Methane> Carbon dioxide> Nitrogen> Hydrogen
[B] Carbon dioxide> Nitrogen> Methane> Hydrogen
[C] Nitrogen> Hydrogen> Carbon dioxide> Methane
[D] Hydrogen> Nitrogen> Methane> Carbon dioxide
Show Answer
Correct Answer: A [ Methane> Carbon dioxide> Nitrogen> Hydrogen ]
Notes:
The correct composition of biogas released through anaerobic bio-digester system is:
Methane (CH4) – 50–75 %
Carbon dioxide (CO2) – 25–50%
Nitrogen (N2) – 0–10%
Hydrogen (H2) – 0–1%
Hydrogen sulphide (H2S) – 0–3%
5. Which of the following is the use of washing soda?
[A] softening of water
[B] manufacture of glass
[C] manufacture of paints
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
It is used for softening of water, laundering, cleaning, manufacture of glass, soap, borax, paper, paints and textile It is also extensively used as laboratory reagent.
6. Bell metal is an alloy of which of the following metals?
[A] Copper and Tin
[B] Copper and Mercury
[C] Copper and Lead
[D] Copper and Zinc
Show Answer
Correct Answer: A [Copper and Tin]
Notes:
Bell metal is a form of bronze with a higher tin content. It is an alloy of copper and tin (typically, 78% copper, 22% tin by mass). It is used for making bells and related instruments, such as cymbals.
7. What is Rose metal?
[A] It is an alloy of Nickel, Tin and Zinc
[B] It is an alloy of Bismuth, Copper and Palladium
[C] It is an alloy of Palladium, Tin and Lead
[D] It is an alloy of Bismuth, Tin and Lead
Show Answer
Correct Answer: D [It is an alloy of Bismuth, Tin and Lead]
Notes:
Rose metal is an alloy of Bismuth, Tin and Lead. It’s a fusible alloy with low melting point commonly used for soldering.
8. Which of these methods can be used to prevent rancidity?
[A] Adding antioxidants to the food
[B] Storing food at low temperature
[C] Replace the air with nitrogen in the packing material
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
When food containing fats and oils are exposed to the atmosphere, the oxidation of fat and oil occurs, this is called as Rancidity.
9. In which of the following groups is Gold placed in the modern periodic table?
[A] 10
[B] 12
[C] 11
[D] 9
Show Answer
Correct Answer: C [11]
Notes:
Gold, with the atomic number of 79 is classified under group 11 of the modern periodic table. This group also contains silver and copper and is often referred to as the coinage metals due to their historical use in coins. They are known for their high electrical conductivity, resistance to tarnish, and are extremely malleable and ductile.
10. 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.
