Which of the following has maximum number of atoms? (a) 18g of H2O (b) 18g of O2 (c) 18g of CO2 (d) 18g of CH4
ScienceClass 9CBSEAnswered 27 Mar 2026
Answer
Soln:
Answer is (d) 18g of CH4
Explanation:
Number of atoms = Mass of
substance × Number of atoms in the molecule/ Molar mass × NA
- 18 g of water =18 x3/18 ×NA = 3 NA
- 18 g of oxygen = 18 x2 /32 × NA = 12 NA
- 18 g of CO2 = 18 x3/44 × NA = 23 NA
- 18 g of CH4 =18 x5 /16 × NA = 5.63 NA
Note: NA = 6.023×1023
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