Assertion and Reason Questions for Class 11 Chemistry Chapter 1 Some Basic Concepts of Chemistry

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Assertion and Reason Questions for Some Basic Concepts of Chemistry

Directions : Each of these questions contain two statements, Assertion and Reason. Each of these questions also has four alternative choices, only one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

Q.1. Assertion : Equal moles of different substances contain same number of constituent particles.
Reason : Equal weights of different substances contain the same number of constituent particles.

Answer Answer: (c) Equal moles of different substances contain same number of constituent particles but equal weights of different substances do not contain the same number of constituent particles.

Q.2. Assertion : 1.231 has three significant figures.
Reason : All numbers right to the decimal point are significant.

Answer Answer: (d) 1.231 has four significant figures all no. from left to right are counted, starting with the first digit that is not zero for calculating the no. of significant figure.

Q.3. Assertion : Volume of a gas is inversely proportional to the number of moles of gas.
Reason : The ratio by volume of gaseous reactants and products is in agreement with their mole ratio.

Answer Answer: (d)


Q.4. Assertion : Significant figures for 0.200 is 3 whereas for 200 it is 1.
Reason : Zero at the end or right of a number are significant provided they are not on the right side of the decimal point.

Answer Answer: (c)

Q.5. Assertion : One atomic mass unit is defined as one twelfth of the mass of one carbon – 12 atom.
Reason : Carbon-12 isotope is the most abundant isotope of carbon and has been chosen as standard.

Answer Answer: (b)

Q.6. Assertion : The empirical mass of ethene is half of its molecular mass.
Reason : The empirical formula represents the simplest whole number ratio of various atoms present in a compound.

Answer Answer: (a)

Q.7. Assertion: The number of O atoms in 16 g of oxygen and 16 g of ozone is same. 
Reason:
Each of the species represent 1 g-atom of oxygen.

Answer Answer: (a)

Q.8. Assertion: 1 mole of sulphuric acid contains 32 g each of sulphur and oxygen element.
Reason: 1 mole of sulphuric acid represents 98 g of the species.

Answer Answer: (d)

Q.9. Assertion: 1 mole of H2SO4 is neutralised by 2 moles of NaOH but 1 equivalent of H2SO4 is neuralised by 1 equivalent of NaOH.
Reason: Equivalent wt. of H2SO4 is half of its moleculer wt. while equivalent wt. of NaOH is 40.  

Answer Answer: (b)

Q.10. Assertion: 1 Avogram is equal to 10 amu.
Reason: Avogram is reciprocal of Avogadro number.          

Answer Answer: (d)

Q.11. Assertion: The ash produced by burning Mg in air is lighther than the original mass of Mg.
Reason: Mg burns in air to produce MgO2 and Mg3N2.         

Answer Answer: (d)

Q.12. Assertion: Vapour density of sulphur vapour relative to oxygen is 2 because sulphur atom is twice as heavy as that of O atom.
Reason: Vapour density depends upon the molecular state of the substance in solid state.

Answer Answer: (d)

Q.13. Assertion: Equal volumes of all the gases contain equal number of atoms.
Reason: Atom is the smallest particle which takes part in chemical reactions.  

Answer Answer: (d)

Q.14. Assertion: The ratio by volume of gaseous reactants and products is in agreement with their molar ratio.
Reason: Volume of a gas is inversely proportional to the number of moles of a gas.        

Answer Answer: (c)

Q.15. Assertion: One mole of SO2 contains double the number of molecules present in one mole of O2.
Reason: Molecular weight of SO2 is double to that of O2.              

Answer Answer: (d)

Q.16. Assertion: The compounds NaCl and CaO do not exists as discrete molecules.
Reason: For a substance that does not exist as discrete molecules, the formula weight and the molecular weight are identical.                       

Answer Answer: (b)

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