All Free Chemistry MCQs with Answers
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13,720 questions · page 685 of 686
13681. If an atom exists in the excited state n = 5, the maximum number of transitions that take place are:
- A. 6
- B. 5
- C. 10
- D. 3
Explanation: To solve such a question, here's an amazing trick! We know that n is 5. Step 1: From the 'n' value, start counting backwards. i.e.
Correct answer: 10- A. 2 times
- B. 3 times
- C. 4 times
- D. 5 times
Explanation: Since r = n^2 (0.053nm) When n = 1 r1 = 0.053nm When n = 2 r2 = 2^2 (r1) r2 = 4 r1 An increase in the radius of orbit when an electron…
Correct answer: 3 times- A. 13.6 eV
- B. 1.36 eV
- C. 10.2 eV
- D. 4.3 eV
Explanation: The ionization potential of a hydrogen atom is 13.6 eV, which is the energy needed to completely remove the electron from the nucleus when…
Correct answer: 13.6 eV- A. Increases with increasing energy
- B. Decreases with increasing energy
- C. First increases and then decreases with increasing energy
- D. First decreases and then increases with increasing energy
Explanation: As energy levels increase, the energy difference between adjacent ones decreases due to the trend of decreasing energy from the energy…
Correct answer: Decreases with increasing energy- A. 1.51 eV
- B. 3.4 eV
- C. 13.6 eV
- D. 12.1 eV
Explanation: The energy required to ionize a hydrogen atom from a given state is the difference between the energy of that state and the energy of the…
Correct answer: 1.51 eV- A. The size of the electrode
- B. The pH of the solution
- C. The amount of metal in the anode
- D. The values of the half cell
Explanation: For a galvanic cell, emf can be calculated by standard reduction potentials for two half cells.
Correct answer: The values of the half cell13687. Which statement is correct:
- A. Standard Hydrogen Electrode SHE always acts as anode
- B. SHE may act as cathode or anode depending upon the reduction potential of the counterpart
- C. SHE always acts as cathode in voltaic cell
- D. None of the above
Explanation: SHE may act as cathode or anode depending upon the reduction potential of the counterpart: This statement is correct.
Correct answer: SHE may act as cathode or anode depending upon the reduction potential of the counterpart- A. 22.4 dm3
- B. 2.24 dm3
- C. 4.48 dm3
- D. 44.8 dm3
Explanation: Moles of N 2 =2.8/28=0.1 moleAtS.T.P: mole→22.4 L ∴0.1 mole →2.24 L=2240 ml=2240cc=2.24 dm3
Correct answer: 2.24 dm3- A. 22.4 dm3
- B. 2.24 dm3
- C. 11.2 dm3
- D. 16.0 dm3
Explanation: At STP, one mole of any ideal gas occupies 22.4 dm3. The molar mass of oxygen (O2) is 32 g/mol.
Correct answer: 2.24 dm3- A. 2.24dm3
- B. 1.12dm3
- C. 22.4dm3
- D. 24dm3
Explanation: To find the volume of 1.6 g of O2 at STP (Standard Temperature and Pressure), we can use the ideal gas law equation: PV = nRT.
Correct answer: 2.24dm3- A. 1.12 dm3
- B. 2.24 dm3
- C. 22.4 dm3
- D. 24 dm3
Explanation: Option B is correct. The volume occupied by 3.2 g of oxygen gas at STP is 2.24 dm3.
Correct answer: 2.24 dm3- A. Simple diffusion
- B. Fractional distillation
- C. Chromatography
- D. Graham's law of diffusion
Explanation: Fractional distillation is the special technique which is used for separation of mixture of two gases
Correct answer: Fractional distillation- A. NaHCO3
- B. CaCO3.H2O
- C. CaCl2 anhydrous
- D. Na2SO4.H2O
Explanation: CaCl2 (anhydrous calcium chloride): Calcium chloride is a widely used drying agent due to its strong hygroscopic properties.
Correct answer: CaCl2 anhydrous- A. Theoretical yield
- B. Practical yield
- C. Percentage yield
- D. All of above
Explanation: Stoichiometry uses the balanced chemical equation to calculate how much product can theoretically form from given amounts of…
Correct answer: Theoretical yield- A. 2.0 X27/150 x100
- B. 2.0/10 X 2 X 27/150 X 100
- C. 2.0/10 X 27/1500 X 100
- D. 2.0/10 X 150/3 X 27 X 100
Explanation: Mass of aluminum in formula: 2×27=54 gMolar mass of Al₂S₃: 2×27+3×32=54+96=150 g54/150x100=36%
Correct answer: 2.0 X27/150 x100- A. Corrosion
- B. Sotubility
- C. Melting point
- D. Boiling point
Explanation: A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance.
Correct answer: Corrosion- A. closed system
- B. open system
- C. isolated system
- D. None of the above
Explanation: Thermoflask will not allow the exchange of matter and energy with the surrounding environment.
Correct answer: isolated system- A. Heat capacity
- B. 1 Joule
- C. Specific beat
- D. One calorie
Explanation: The Correct MCQ should be "The amount of heat required to raise the temperature of 1g of substance through 1K is called" Specific heat is…
Correct answer: Specific beat13699. For all adiabatic processes:
- A. The entropy of the system does not change
- B. The entropy of the system increases
- C. The entropy of the system decreases
- D. The entropy of the system does not decrease
Explanation: Essential conditions for the adiabatic process to take place are: i) System is perfectly insulated from surrounding.
Correct answer: The entropy of the system does not decrease- A. Clausius
- B. Carrot
- C. Pascal
- D. Kelvin
Explanation: Rudolf Clausius, a German physicist, introduced the concept of entropy in the study of thermodynamics.
Correct answer: Clausius