Some Basic Concepts Of Chemistry Question 211
Question: The number of molecules in 4.25 g of ammonia are [Pb. CET 2000]
Options:
A) $ 0.5\times 10^{23} $
B) $ 1.5\times 10^{23} $
C) $ 3.5\times 10^{23} $
D) $ 1.8\times 10^{32} $
Show Answer
Answer:
Correct Answer: B
Solution:
Molecular weight of $ NH _3 $ is 17 According to the mole concept $ 17,gm $ $ NH _3 $ has molecules $ =6.02\times 10^{23} $
$ \therefore 1,gm $ $ NH _3 $ has molecules $ =\frac{6.02\times 10^{23}}{17} $
$ \therefore $ $ 4.25,gm $ $ NH _3 $ has molecules $ =\frac{6.02\times 10^{23}\times 4.25}{17}=1.5\times 10^{23},molecule $
