Question

Find the no. of molecules in the following:-
A. 0.25mole pf oxygen gas
B. 66g CO2

Answer 1

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A ) 0.25 mole of Oxygen gas

No of. molecules = 0.25 × 6.022 × 10²³ = 1.5055 × 10²³

B) 66g of CO2

$no. \: of \: molecules \: = \frac{given \: mass}{molar \: mass} \times avg \: no. \\ \\ given \: mass \: = 66g \\ \\ molar \: mass \: = 16 \times 2 + 12 = 44g \\ \\ no \: of \: molcules = \frac{66}{44} \times 6.022 \times {10}^{23} = 9.033 \times {10}^{23}$


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