Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. What is the key element used in the batteries of electric vehicles?
[A] Magnesium
[B] Lithium
[C] Sodium
[D] Bromine
Show Answer
Correct Answer: B [Lithium]
Notes:
The primary component for electric vehicle batteries is Lithium, used as Lithium carbonate or Lithium hydroxide. These Lithium-ion batteries have a high power-to-weight ratio, energy efficiency, and thermal stability, leading to their prevalence in electric vehicles. Notably, the boom in EVs has significantly driven the demand for Lithium globally.
2. “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).
3. Mizoroki-Heck reaction is catalyzed by which of the following metals?
[A] Rhodium
[B] Sodium
[C] Palladium
[D] Osmium
Show Answer
Correct Answer: C [Palladium]
Notes:
The Mizoroki-Heck reaction is a cross-coupling reaction that typically involves the coupling of aryl halides with alkenes. It is primarily catalyzed by palladium (Pd) complexes. Palladium is favored due to its ability to facilitate the oxidative addition and reductive elimination steps essential for the reaction. Rhodium, while also a transition metal, is less commonly used for this specific reaction. The Mizoroki-Heck reaction is important in organic synthesis for forming carbon-carbon bonds and is widely utilized in pharmaceuticals and materials science.
4. Pyrolusite, Braunite, Psilomelane, Rhodochrosite are the ores of which among the following metals?
[A] Manganese
[B] Aluminium
[C] Copper
[D] Manganese and Copper
Show Answer
Correct Answer: A [Manganese]
Notes:
Pyrolusite, Braunite, Psilomelane, and Rhodochrosite are all ores of Manganese. Pyrolusite is one of the most important ores due to its high manganese content. Braunite, although a significant ore, its manganese content is less than Pyrolusite. Psilomelane and Rhodochrosite also contribute as minor ores.
5. How many electrons can the s-orbital accommodate?
[A] 1
[B] 2
[C] 8
[D] 16
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Correct Answer: B [2]
Notes:
A the s-orbital can accommodate only two electrons, two groups (1 & 2) belong to the s-block of the Periodic Table.
6. Which of the following is NOT correct about Group 14 elements?
[A] All of them are solids
[B] Melting points are much higher than those of corresponding elements of group 13
[C] Carbon is a non-metal
[D] Germanium is a metal
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Correct Answer: D [Germanium is a metal]
Notes:
All members of group 14 are solids. Carbon and silicon are non-metals, germanium is a metalloid, whereas tin and lead are soft metals. Melting points and boiling points of group 14 elements are much higher than those of corresponding elements of group 13.
7. What is the relationship between becquerel and curie unit?
[A] 1 curie = 0.5 Bq
[B] 1 curie = 9 × 106 Bq
[C] 1 curie = 3.7 × 1010 Bq
[D] 1 curie = 5.7 Bq
Show Answer
Correct Answer: C [1 curie = 3.7 × 1010 Bq]
Notes:
1 curie = 1 Ci = 3.7 × 1010 decays per second = 3.7 × 1010 Bq. This is approximately the amount of radioactivity emitted by one gram (1 g) of radium-226. The ‘curie’ unit is named after Pierre Curie, a French physicist.
8. What is the change in the rate constant for a chemical reaction when temperature rises by 10° C?
[A] The rate constant is constant
[B] The rate constant is nearly doubled
[C] The rate constant is nearly halved
[D] The rate constant becomes four times
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Correct Answer: B [The rate constant is nearly doubled]
Notes:
For a chemical reaction with rise in temperature by 10°, the rate constant is nearly doubled. Most of the chemical reactions are accelerated by increase in temperature.
9. Which of these species will have the largest atomic size?
[A] Na
[B] Mg
[C] Mg2+
[D] K
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Correct Answer: D [K]
Notes:
Atomic size increases down the group as new shells are added. Therefore, Potassium (K) will have the largest size among the given elements as it belongs to the 4th period where as other elements belong to 3rd period.
10. What is the bond formed due to the electrostatic attraction known as?
[A] Covalent bond
[B] Electrovalent bond
[C] Electromagnetic bond
[D] Polar bond
Show Answer
Correct Answer: B [Electrovalent bond]
Notes:
The bond formed, as a result of the electrostatic attraction between the positive and negative ions is termed as Electrovalent bond. It is also known as Ionic bond.