Question

Arrange the following in order of increasing mass :
(i) 1 mole of N2, (ii) 0.5 mole of O3, (iii) $3.011×10^{23}$ molecules of O2, (iv) 0.5 gram atom of O2

• A. iv<iii<ii<i
• B. iv<i<iii<ii
• C. iii<ii<iv<i
• D. i<iii<ii<iv

Answer 1

Answer: (A)

iv<iii<ii<i

Answer 2

The mass of the substance is calculated by multiplying the number of moles of the substance by its molar mass.

For example, the mass of O3 can be found as follows: Mass of O3 = 0.5 moles × 48 g/mol = 24 g

II) One gram atom is equivalent to one mole. Thus, the mass of oxygen (O) is determined by multiplying the number of moles by its molar mass.

For instance, the mass of O in the context could be calculated like this: Mass of O = 0.5 moles × 16 g/mol = 8 g

III) The relationship between moles and molecules is that 1 mole is equal to 6.022 × 10^23 molecules. Consequently, the number of moles of O2 can be determined by dividing the given number of molecules by Avogadro's number.

As an illustration, the moles of O2 can be calculated as follows: Moles of O2 = 6.022×10233.011×10233.011×10236.022×1023​ = 0.5 moles

The mass of O2 can then be found: Mass of O2 = 0.5 moles × 32 g/mol = 16 g

IV) The volume occupied by 1 mole of a gas at NTP (Normal Temperature and Pressure) is 22.4 L. By using this information, the number of moles of CO2 can be calculated based on the given volume.

For instance, the moles of CO2 can be determined as follows: Moles of CO2 = 22.45.65.622.4​ = 0.25 moles

The mass of CO2 can then be calculated: Mass of CO2 = 0.25 moles × 44 g/mol = 11 g

The correct answer is option (A): iv<iii<ii<i