All Free Chemistry MCQs with Answers
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13,720 questions · page 576 of 686
- A. it occupies 2.24 litre at STP
- B. it corresponds to same mole of CO and N2
- C. it corresponds to 0.5 mol f CO
- D. it corresponds to 3.01 x 10^23 molecules of CO
Explanation: Explanation for this question will be added soon!
Correct answer: it occupies 2.24 litre at STP11502. One mole of CO2 contains
- A. 6.02 x 10^23 atoms of C
- B. 6.02 x 10^23 atoms of O
- C. 8.1 x 10^23 atoms of CO2
- D. Option D
Explanation: Explanation for this question will be added soon!
Correct answer: 6.02 x 10^23 atoms of C11503. Choose the wrong statement.
- A. 1 mole means 6.023 x 10^23 particles
- B. Molar mass is mass of 1 molecule
- C. Mole is mass of 1 mole of substance
- D. Molar mass is molecular mass expressed in grams
Explanation: Explanation for this question will be added soon!
Correct answer: Molar mass is mass of 1 molecule- A. Mass of compound/Mass of element -x100
- B. Mass of molecule/Mass of compound x100
- C. Mass of element/Mass of molecule x100
- D. Mass of element/Mass of compound x1000
Explanation: An explanation for this question has been added!
Correct answer: Mass of element/Mass of molecule x10011505. 1 atomic mass unit=_kg
- A. 1.66×10-²⁷
- B. 2.45×10-³¹
- C. 2.77×p10³⁴
- D. 9.34×10-²⁵
Explanation: Fact, learn it (it is 1/12th the mass of Carbon-12).
Correct answer: 1.66×10-²⁷- A. why do isotopes have different physical properties?
- B. Isotopes have same atomic number
- C. Isotopes of an element have different mass number
- D. Isotopes of an element have different atomic number
Explanation: The variation of atomic mass in isotopes can influence its physical properties like Density, Melting and boiling point and stability.
Correct answer: Isotopes of an element have different mass number- A. 64g
- B. 32g
- C. 100g
- D. 71g
Explanation: Mole= Mass/ relative atomic mass. Mass = Mole x Relative atomic mass Mass= 2 x 32(Because oxygen gas written so it means O2, O is 16 so O2…
Correct answer: 64g- A. Number of ions
- B. Empirical formula of organic compounds
- C. Structure formula
- D. Isotope of an element
Explanation: Combustion analysis provides valuable information for determining the empirical formula or molecular formula of an organic compound by…
Correct answer: Empirical formula of organic compounds- A. chemical change
- B. Physical change
- C. Neither chemical nor physical change
- D. .
Explanation: 2 KOH + CO₂ → K₂CO₃ + H₂O It is a chemical change because it involves breaking and forming new chemical bonds.
Correct answer: chemical change- A. C3H404
- B. C2H2O
- C. C2H2O4
- D. C2HO2
Explanation: C : H : O 34.6/12 :3.5/1 : 61.5/16 3 : 4 : 4 => E:F= C3H4O4 =>E.F.Mass= (3x12)+(1x4)+(4x16) = 104 => n= Molecular Mass/ E.F.Mass = 104/104…
Correct answer: C3H404- A. 80 moles of atoms
- B. 40 moles of hydrogen atom
- C. 30 moles of electrons
- D. 30 moles of oxygen atoms
Explanation: 2H + O --> H2O H : H2O 2 : 1 X : 20 X=40 moles of hydrogen atom. (Correct)
Correct answer: 40 moles of hydrogen atom- A. 2.24 dm3
- B. 112cm3
- C. 22.4dm3
- D. 1.12dm3
Explanation: Moles = Mass / Mr = 4.4 / 48 = 0.1 ● Volume= Mole x 22.4 dm3(in STP) = 0.1 x 22.4 = 2.24 dm3
Correct answer: 2.24 dm3- A. 4.3×10-³
- B. 4.01×10-²
- C. 4.03×10-¹
- D. 4.3×10-²
Explanation: Ar of Na= 23g/mol Mole=Mass/Mr Mole= 0.1/23 Mole= 4.3x10^-3
Correct answer: 4.3×10-³- A. One mole of water
- B. One mole of CH4
- C. One mole of glucose
- D. One mole of H2O2
Explanation: This answer is correct because one mole of glucose has highest number of atoms.
Correct answer: One mole of glucose- A. A limiting reagent is consumed at the end of the reaction
- B. Actual yield is always greater than theoretical yield
- C. Stoichiometric calculation can be only done if no side reaction happens
- D. The empirical formula in molecular formula of some of the compounds are same
Explanation: Actual yield is less than theoretical yield due to the following reasons i) side reactions may produce by-products ii) some reactions are…
Correct answer: Actual yield is always greater than theoretical yield- A. 24.5g H2SO4
- B. This answer is incorrect because the non limiting reagent is NaOH (in excess).
- C. 46.5g NaOH
- D. 60g NaOH
Explanation: Mr of NaOH= 23 + 16 + 1 = 40g/mol Mr of H2SO4= (2x1) + 32 + (4x16) = 98g/mol 2NaOH + H2SO4 => Na2SO4 +2H2O 2x40g. 98g. xg.
Correct answer: 46.5g NaOH- A. 50 g
- B. 72g
- C. 36g
- D. 54g
Explanation: This answer is incorrect because the number of moles of water produced is not 3.
Correct answer: 54g- A. CaCO3 is limiting reagent
- B. Both are consumed completely
- C. HCL is limiting reagent
- D. There is no reaction
Explanation: the equation for the reaction is CaCO3 + 2HCl → CO2 + H2O + CaCl2 Mr of HCl= 1 + 35.5 = 36.5 Mr of CaCO3= 40 + 12 + (3x16) = 100 2x36.5g…
Correct answer: CaCO3 is limiting reagent- A. When mole of H2O is produced
- B. All the oxygen is consumed
- C. 1.5 mole of NO is formed
- D. All the ammonia is consumed
Explanation: 4NH3 => 5O2 xNH3 => 1O2 x= 0.8mol As oxygen is the limiting factor it will be consumed first.
Correct answer: All the oxygen is consumed- A. Actual yield
- B. Percentage yield
- C. Theoratical yield
- D. None
Explanation: Theoretical yield is the maximum amount of product that can be obtained from a given amount of reactant, assuming that the reaction goes…
Correct answer: Theoratical yield