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 iron ore contains the highest percentage of iron content?
[A] Hematite
[B] Siderite
[C] Magnetite
[D] Limonite
Show Answer
Correct Answer: C [Magnetite]
Notes:
Magnetite (Fe3O4) typically contains about 70% iron by weight. It is black in color and strongly magnetic. Hematite (Fe2O3) contains about 60–70% iron. Limonite contains 35–50% iron. Siderite (FeCO3) contains about 48% iron. Magnetite is widely mined due to its high iron concentration compared to other ores.
2. Which among the following is the most abundant organic compound in nature?
[A] Glucose
[B] Fructose
[C] Sucrose
[D] Cellulose
Show Answer
Correct Answer: D [Cellulose]
Notes:
Cellulose is the most abundant organic compound in nature. It is the main constituent of plant fiber. Plants contain on average 33% cellulose, and cotton is the purest form at 90%. Chitin is the second most abundant organic compound in nature.
3. Which among the following is the property of Tungsten which makes it eligible to use in the bulbs?
[A] highest melting point
[B] highest resistance
[C] Highest malleability
[D] All are correct
Show Answer
Correct Answer: A [highest melting point]
Notes:
The electric heating is also used to produce light, as in an electric bulb. Here, the filament must retain as much of the heat generated as is possible, so that it gets very hot and emits light. It must not melt at such high temperature. A strong metal with high melting point such as tungsten (melting point 3380°C) is used for making bulb filaments. The filament should be thermally isolated as much as possible, using insulating support, etc. The bulbs are usually filled with chemically inactive nitrogen and argon gases to prolong the life of filament. Most of the power consumed by the filament appears as heat, but a small part of it is in the form of light radiated.
4. 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.
5. Which of the following catalyst is used generally during the hydrogenation of Alkenes?
[A] Platinum
[B] Palladium
[C] Nickel
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Dihydrogen gas adds to alkenes and alkynes in the presence of finely divided catalysts like platinum, palladium or nickel to form alkanes.
6. What is the hemihydrate of calcium sulphate commonly known as?
[A] Gypsum
[B] Plaster of Paris
[C] Chloroform
[D] Limestone
Show Answer
Correct Answer: B [Plaster of Paris]
Notes:
Plaster of Paris is the common name of calcium sulphate hemihydrate because half molecule of water is attached with calcium sulphate. The chemical formula of plaster of Paris is CaSO4.1/2H2O.
7. How is Aqua regia formed?
[A] by mixing 2 parts of concentrated HCl and one part of concentrated HNO3
[B] by mixing 3 parts of concentrated HCl and one part of concentrated HNO3
[C] by mixing 1 part of concentrated HCl and three parts of concentrated HNO3
[D] None of the above
Show Answer
Correct Answer: B [by mixing 3 parts of concentrated HCl and one part of concentrated HNO3]
Notes:
When three parts of concentrated HCl and one part of concentrated HNO3 are mixed, aqua regia is formed which is used for dissolving noble metals, e.g., gold, platinum.
8. Which of the following mixture can be separated by Fractional distillation method?
[A] Air
[B] Crude oil
[C] Chlorosilanes
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Fractional distillation method is used to separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K. example: Air, crude oil, chlorosilanes etc.
9. Which of the following is the correct order in terms of Iron content?
[A] Magnetite > Haematite >Siderite > Limonite
[B] Haematite> Magnetite >Siderite > Limonite
[C] Haematite > Magnetite > Limonite > Siderite
[D] Magnetite > Haematite > Limonite > Siderite
Show Answer
Correct Answer: D [Magnetite > Haematite > Limonite > Siderite]
Notes:
Magnetite > Haemetite > Limonite > Siderite . Magnetite has 72.4% iron content. Haematite has 70% iron content. Limonite has 55% iron content. Siderite has 48.2% iron content.
10. Which of the following equation represents combination of Hydrogen gas with nitrogen to form ammonia?
[A] 2H2 + N –> NH3
[B] 2H + N3 –> NH3
[C] 3H2 + N2 –> 2NH3
[D] None of the above
Show Answer
Correct Answer: C [3H2 + N2 –> 2NH3]
Notes:
3H2 + N2 –> 2NH3 is the balance equation which represents combination of Hydrogen gas with nitrogen to form ammonia.
