A) \[2.85\times {{10}^{-3}}\]
B) \[28.8\times {{10}^{-3}}\]
C) \[0.288\times {{10}^{-3}}\]
D) \[1.68\times {{10}^{-2}}\]
Correct Answer: A
Solution :
200mg of \[C{{O}_{2}}\] = \[200\times {{10}^{-3}}=0.2gm\] 44gm of \[C{{O}_{2}}\] = \[6\times {{10}^{23}}\]molecules 0.2gm of \[C{{O}_{2}}\] = \[\frac{6\times {{10}^{23}}}{44}\times 0.2=0.0272\times {{10}^{23}}\] \[=2.72\times {{10}^{21}}\]molecule Now \[{{10}^{21}}\]molecule are removed. So remaining molecules \[=2.72\times {{10}^{21}}-{{10}^{21}}\] \[={{10}^{21}}(2.72-1)\] =\[1.72\times {{10}^{21}}\] molecules Now, \[6.023\times {{10}^{23}}\]molecules = 1mole \[1.72\times {{10}^{21}}\] molecules \[=\frac{1\times 1.72\times {{10}^{21}}}{6.023\times {{10}^{23}}}=0.285\times {{10}^{-2}}\] \[=2.85\times {{10}^{-3}}\].
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