All Free Chemistry MCQs with Answers
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13,720 questions · page 640 of 686
- A. 1.7588 x 10^-11
- B. 1.7588 x 10^11
- C. 1.602 x 10^-19
- D. 1.7588 x 10^8
Explanation: A is incorrect as given value is not charge of one gram of electrons.B is incorrect as given value is charge of one kilogram of…
Correct answer: 1.7588 x 10^8- A. 1.7588 x 10^-11
- B. 1.7588 x 10^11
- C. 1.602 x 10^-19
- D. 1.7588 x 10^8
Explanation: We know 1 electron has a mass of 9.1x10²⁸g So 1g of electrons have how many number of electrons in it ?
Correct answer: 1.7588 x 10^8- A. Increases.
- B. Decreases.
- C. Remains constant.
- D. Decreases then increases.
Explanation: Paramagnetism is due to the presence of unpaired electrons in the material, so most atoms with incompletely filled atomic orbitals are…
Correct answer: Increases.- A. 1s2,2s2,2p6,3s2,3p6,3d3
- B. 1s2,2s2,2p6,3s2,3p6,4s2,3d1
- C. 1s2,2s2,2p6,3s2,3p6,4s2,4p1
- D. 1s2,2s2,2p6,3s2,3p6,4s1,4p2
Explanation: The electronic configuration for Sc is 1s2, 2s2, 2p6, 3s2, 3p6 and since 4s is filled before 3d, we get 4s2 and 3d1
Correct answer: 1s2,2s2,2p6,3s2,3p6,4s2,3d1- A. 28
- B. 29
- C. 30
- D. 34
Explanation: No of electrons = no of protons = atomic number in a neutral atom. Since Ga-69 has atomic number 31 so its number of electrons is also 31…
Correct answer: 28- A. Molecular
- B. Ionic
- C. Covalent
- D. Metallic
Explanation: Explanation:Electron gas theory was proposed by Drude and Loren. It helps explain the bonding in metals.
Correct answer: Metallic- A. Zn, Cd, Pb
- B. Zn, Cd, Hg
- C. Zn, Cd, Ba
- D. Zn, Cd, Bi
Explanation: Explanation:In modern periodic table, the elements in group ll-B are Zn, Cd, and Hg. This option is not correct.
Correct answer: Zn, Cd, Hg- A. d-orbital
- B. s-orbital
- C. p-orbital
- D. None of the above
Explanation: Explanation:The color of the transition metal ions/compounds is due to the electrons present in d-orbital.
Correct answer: d-orbital- A. Unpaired electrons
- B. Paired electrons
- C. Protons
- D. Neutrons
Explanation: A is correct as the presence of unpaired electrons results in a weak attraction to magnets.An unpaired electron has a magnetic dipole…
Correct answer: Unpaired electrons- A. Central metal ion
- B. Water molecule
- C. Complex ion
- D. Outer anion
Explanation: The central metal ion has the coordination number 4. To bring the electrons from lower to higher energy levels, the photon is absorbed and…
Correct answer: Central metal ion- A. Linear
- B. Square planar
- C. Tetrahedral
- D. Octahedral
Explanation: The cobalt ion is in +3 oxidation state and has an electronic configuration of 3d6.
Correct answer: Octahedral- A. Electrophile
- B. Base
- C. Leaving group
- D. Acid
Explanation: Bases are proton acceptors and OH- is a base as it eliminates H+ (proton) from the reactant and forms a water molecule.
Correct answer: Base- A. Strong bases causes substitution in preference to elimination
- B. Role of leaving groups in elimination is simitar to substitution
- C. Substitution is favored more than elimination by decreasing solvent polarity
- D. Decrease in temperature will favor elimination more than substitution
Explanation: This statement is correct. In both substitution and elimination reactions, the effectiveness of the leaving group plays a crucial role; a…
Correct answer: Role of leaving groups in elimination is simitar to substitution- A. ΔHv
- B. ΔHf
- C. ΔHi
- D. ΔHs
Explanation: The molar heat of fusion (ΔHfus) of a substance is the heat absorbed by one mole of that substance as it is converted from a solid to a…
Correct answer: ΔHf- A. MgCO3 + 2HCl → MgCl2 + CO2 + H2O
- B. KOH + HCl → KCl + H2P
- C. NH4Cl + NaOH → NaCl + H2O + NH3
- D. H2SO4 + Mg(OH)2 → MgSO4 + 2H2O
Explanation: The given reaction depicts a neutralization reaction, where one mole of acid is neutralized by one mole of alkali (as indicated by 1 mole…
Correct answer: H2SO4 + Mg(OH)2 → MgSO4 + 2H2O- A. Zymase
- B. Invertase
- C. Cellulose
- D. Urease
Explanation: Explanation:Concentrated sugar solution undergoes hydrolysis into glucose and fructose by enzyme called Invertase.
Correct answer: Invertase- A. Zymase
- B. Invertase
- C. Urease
- D. Diastase
Explanation: Zymase is the enzyme that catalyses the fermentation of sugar into ethanol and carbon dioxide.
Correct answer: Zymase- A. Concentration
- B. Ratio between the particles
- C. Vapour pressure
- D. Attraction between the phases
Explanation: It's the standard definition of a Freezing point. The freezing point is "the temperature at which the vapor pressure of the substance in…
Correct answer: Vapour pressure- A. amount of liquid
- B. size of molecule
- C. temperature of liquid
- D. intermolecular forces
Explanation: The amount of liquid does not affect the magnitude of vapor pressure. Vapor pressure is primarily determined by the temperature of the…
Correct answer: amount of liquid- A. 200-760 torr
- B. 760-1200 torr
- C. 665-670 torr
- D. 660-700 torr
Explanation: To boil water at 110 °C, the external pressure should be approximately 1.4 atm, which is equivalent to 1,064 torr.
Correct answer: 760-1200 torr