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. 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.
3. Which of the following is a thermosetting plastic?
[A] Polythene
[B] Bakelite
[C] Polyvinyl chloride
[D] Casseine
Show Answer
Correct Answer: B [Bakelite]
Notes:
Bakelite is a thermosetting plastic formed from phenol and formaldehyde, used in electrical insulators and cookware handles. Unlike thermoplastics, it hardens irreversibly when heated and cannot be remolded. It was the first synthetic plastic, invented by Leo Baekeland in 1907.
4. Which among the following types of glasses contains Cerium and other rare earths and has a high absorption of ultraviolet rays?
[A] Crookes Glass
[B] Pyrex Glass
[C] Flint Glass
[D] Crown Glass
Show Answer
Correct Answer: A [Crookes Glass]
Notes:
Crookes glass comprises Cerium oxide (CiO2) which sharply absorbs the ultraviolet rays from the sunlight. It is used in making lenses of eye glasses.
5. Which among the following compound of barium is used as radio contrast agent for X-ray imaging and other diagnostic procedures and also commonly called as Barium Food?
[A] Barium Carbonate
[B] Barium Sulphate
[C] Barium Bromide
[D] Barium hydroxide
Show Answer
Correct Answer: B [Barium Sulphate]
Notes:
Barium Sulphate is the correct answer. It is used as a radiopaque contrast agent in X-ray imaging because it absorbs X-rays, making it visible on the images. Commonly referred to as “Barium Meal” when ingested for gastrointestinal studies, it helps diagnose conditions like ulcers and tumors. Barium Sulphate is insoluble in water, ensuring it remains in the digestive tract without being absorbed.
6. Buckeyballs are basically the allotropes of _________?
[A] Carbon
[B] Sulfur
[C] Phosphorus
[D] Calcium
Show Answer
Correct Answer: A [Carbon]
Notes:
Buckeyballs, or fullerenes, are allotropes of carbon. Discovered in 1985, they consist of 60 carbon atoms arranged in a spherical shape, resembling a soccer ball. This unique structure contributes to their remarkable properties, including high strength and electrical conductivity. Fullerenes are part of a broader class of carbon allotropes, which also includes graphite and diamond.
7. What characteristic of silica gel, a granular form of silica produced from sodium silicate, enables it to control humidity and prevent spoilage or degradation when packaged with various products?
[A] Its high thermal conductivity
[B] Its hygroscopic properties
[C] Its high reflectivity
[D] Its low thermal conductivity
Show Answer
Correct Answer: B [Its hygroscopic properties]
Notes:
Silica gel possesses hygroscopic properties, meaning it can absorb and hold water vapour. This makes it an effective desiccant or drying agent. When packaged with products, silica gel can help control humidity and prevent spoilage or degradation by absorbing excess moisture. This property is particularly valuable when shipping or storing items that can be negatively impacted by damp conditions, like electronics, food, and leather goods.
8. Which of the following is not a metalloid?
[A] Boron
[B] Silicon
[C] Germanium
[D] Titanium
Show Answer
Correct Answer: D [ Titanium]
Notes:
The most commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. The other less recognised metalloids are: carbon, aluminium, selenium, polonium and astatine.Titanium is a lustrous transition metal with a silver color, low density and high strength.
9. 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.
10. Which method will is most suitable to separate the mixture of ammonium chloride and salt?
[A] Evaporation
[B] Sublimation
[C] Simple Distillation
[D] All of the above
Show Answer
Correct Answer: B [Sublimation]
Notes:
Sublimation is the property of substance in which they are converted directly from solid to gas or vice versa. Ammonium chloride is a sublime solid.
