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 energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state is called?
[A] Electron Affinity
[B] Reducing Potential
[C] Ionization Potential
[D] Shell Potential
Show Answer
Correct Answer: C [Ionization Potential ]
Notes:
Ionization potential is the energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state. As we move down the group, ionization potential decreases. As we move across the period, ionization potential increases Electron affinity is the energy released on adding an electron to the outermost shell of an atom in its isolated gaseous state.
2. Which among the following elements are generally find in free state?
[A] Group 11 elements
[B] Group 12 elements
[C] Group 13 elements
[D] Group 14 elements
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Correct Answer: A [Group 11 elements ]
Notes:
Group 11 is also known as the coinage metals, due to their former usage. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form.
3. “Atoms can neither be created nor destroyed.” This principle was given by __?
[A] Avogadro
[B] Dalton
[C] Rutherford
[D] Niels Bohr
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Correct Answer: B [Dalton]
Notes:
The given principle is one of the postulates of the Dalton’s atomic theory given in 1803 by John Dalton. The postulates of Dalton’s atomic theory are as follows:
1. Elements consist of indivisible small particles (atoms).
2. All atoms of the same element are identical; different elements have different types of atom.
3. Atoms can neither be created nor destroyed.
4. ‘Compound elements’ (i.e. Compounds) are formed when atoms of different elements join in simple ratios to form ‘compound atoms’ (i.e. Molecules).
4. Which acid is described as HOOCCOOH?
[A] Oxalic Acid
[B] Acetic Acid
[C] Carbonic Acid
[D] Citric Acid
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Correct Answer: A [Oxalic Acid]
Notes:
Oxalic acid is an organic compound with the formula C₂H₂O₄. Some call it “crab acid” due to its appearance. Its condensed formula is HOOCCOOH, reflecting its classification as the simplest dicarboxylic acid.
5. Calcium Magnesium Silicate is commonly called as ________?
[A] Asbestos
[B] Borax
[C] Baking Soda
[D] Washing Soda
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Correct Answer: A [Asbestos]
Notes:
CaMgO4Si is the chemical formula of calcium magnesium silicate . Calcium magnesium silicate is commonly known as Asbestos. Asbestos is a fibrous silicate mineral as the substance is formed by miniature crystal fibers, these crystal are loosely attached releasing dust of silicate crystal upon small touch.
6. Which of the following processes commonly use the method of adsorption?
[A] Scrubbers manufacturing
[B] Purification of solid substances
[C] Chromatography
[D] Purification of liquid substances
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Correct Answer: C [Chromatography]
Notes:
Adsorption, the binding of gas or liquid particles to a solid surface, is often used in chromatography – a laboratory technique for the separation of a mixture. This process is critical as it allows the separation of the compounds in the mixture, thereby enabling further analysis or purification. Apart from chromatography, adsorption is also used in scrubbers and purification of solids and liquids.
7. Ground Level Ozone is formed due to reaction between:
[A] VOCs, Oxides of Nitrogen & Sunlight
[B] VOCs, Sulphur dioxide & Sunlight
[C] Ozone, Sulphur dioxide & Oxides of Nitrogen
[D] Ozone, Oxides of Nitrogen & Sunlight
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Correct Answer: A [VOCs, Oxides of Nitrogen & Sunlight]
Notes:
Ground Level Ozone results from photochemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.
8. Consider the following:
- Hydrogen (H2)
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
- Methane (CH4)
Which of the above is/are component(s) of high-quality (100% pure) Syngas?
[A] 1 Only
[B] 1 & 2 Only
[C] 1, 2 & 3 Only
[D] 1, 2, 3 & 4
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Correct Answer: B [ 1 & 2 Only]
Notes:
The high-quality (100% Pure) Syngas has the main components of (H2 + CO)
9. Which of the following is the softest metal?
[A] Cesium
[B] Lead
[C] Gold
[D] Silver
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Correct Answer: A [ Cesium]
Notes:
Cesium is extremely reactive metal. It reacts with water even at −116 °C (−177 °F). It is the least electronegative element. Cesium is also the softest known metal. It is so soft that it can be cut with a butter knife.
10. Which of the following alkali metal ions has the highest hydration enthalpy?
[A] Lithium
[B] Sodium
[C] Potassium
[D] Caesium
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Correct Answer: A [Lithium]
Notes:
Lithium ions has maximum degree of hydration and for this reason lithium salts are mostly hydrated.