Question
Question: Which of the following contain the maximum number of molecules? A. \(1g{\text{ }}C{O_2}\) B. \(1...
Which of the following contain the maximum number of molecules?
A. 1g CO2
B. 1g N2
C. 1g H2
D. 1g CH4
Solution
We can solve the above problem with the help of mole concept. According to it, the mass of one mole of atoms is equal to the gram atomic mass. The formula used is:
Number of molecules in “w” gram of an element =gram molecular massw×6.023×1023
Complete step by step answer: In case of 1g of CO2, let us calculate the gram molecular mass of CO2. As we know the gram atomic mass of C is 12g and the gram atomic mass of O is 16g. Then the gram atomic mass of CO2 is calculated as given below:
12+2×16 ⇒12+32=44g
Number of molecules in 1g of CO2 is calculated as below:
441×6.023×1023
⇒446.023×1023=0.1368×1023
Now in the case of 1g of N2, as we know the gram atomic mass of N2 is 28g. Then the number of molecule is calculate as below:
281×6.023×1023=0.21×1023
For the case of 1g of H2 ,the gram atomic mass of H2 is 2g. The the number of molecules is calculated as below:
21×6.023×1023=3.011×1023
For 1g CH4.The gram atomic mass of methane is
12+4=16g
Number of molecules are:
161×6.023×1023=0.376
Hence the correct answer is option C.
Note: The number of molecules can be alternatively calculated as:
If we take the case of CO2, 44g of the CO2 contains molecules=6.023×1023. So, the number of molecules in 1g of carbon dioxide is calculated as below:
446.023×1023=0.136×1023
Now, if we consider the case of N2, 28g of nitrogen contains molecules =6.023×1023. So 1g of nitrogen contains
286.023×1023=0.215 molecules
For the case of H2, 2g of hydrogen contains molecules= 6.023×1023. So 1 g of hydrogen contains
26.023×1023=3.0115 molecules
For the case of CH4, 16g of the methane contain molecules=6.023×1023. So 1g of methane contains
166.023×1023=0.376 molecules