In the following questions two or more options may be correct.

One mole of oxygen gas at STP is equal to _______.

(i) 6.022 × 10²³ molecules of oxygen

(ii) 6.022 × 10²³ atoms of oxygen

(iii) 16 g of oxygen

(iv) 32 g of oxygen

<p>This is a Multiple Choice Questions as classified in NCERT Exemplar</p><p>Option (A), (D)</p><p>One mole of oxygen gas at STP is equal to&nbsp; 6.022 x 10²³&nbsp; molecules of oxygen The number of moles is given by the following formula,</p><p>Moles = <span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mi mathvariant="normal">M</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">s</mi> </mrow> </mrow> <mrow> <mrow> <mi mathvariant="normal">M</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span>&nbsp;&nbsp;&nbsp;----------(1)</p><p>The number of moles of O₂ is calculated by using equation (1) as follow.</p><p>Moles of O_2&nbsp;=<span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mn>16</mn> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">g</mi> </mrow> </mrow> <mrow> <mrow> <mn>32</mn> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">g</mi> <mi mathvariant="normal"> </mi> <mo>/</mo> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span></p><p><strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </strong>= 0.5 mol</p><p>The number of molecules can be calculated as, number of moles</p><p>= <span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">f</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">c</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">s</mi> </mrow> </mrow> <mrow> <mrow> <mi mathvariant="normal">A</mi> <mi mathvariant="normal">v</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">g</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">d</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span>&nbsp;&nbsp;----------(2)</p><p>On substituting the values in the above equation:</p><p>0.5 mol =<span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">f</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">c</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">s</mi> </mrow> </mrow> <mrow> <mrow> <mn>6.022</mn> <mo>×</mo> <mi mathvariant="normal"> </mi> <msup> <mrow> <mrow> <mn>10</mn> </mrow> </mrow> <mrow> <mrow> <mn>23</mn> </mrow> </mrow> </msup> <mi mathvariant="normal"> </mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span></p><p>number of molecules = 0.5 <span contenteditable="false"> <math> <mo>×</mo> </math> </span>&nbsp;6.022 <span contenteditable="false"> <math> <mo>×</mo> </math> </span>10²³</p><p>The number of moles is given by the following formula,</p><p>moles = <span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mi mathvariant="normal">M</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">s</mi> </mrow> </mrow> <mrow> <mrow> <mi mathvariant="normal">M</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span>&nbsp;----------(1)</p><p>The number of moles of O₂ is calculated by using equation (1) as follows,</p><p>Moles of O₂ =<span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mn>32</mn> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">g</mi> </mrow> </mrow> <mrow> <mrow> <mn>32</mn> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">g</mi> <mi mathvariant="normal"> </mi> <mo>/</mo> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> </mrow> </mrow> </mfrac> </math> </span></p><p>=1 mol</p><p>The number of molecules can be calculated as, number of moles</p><p>= <span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">f</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">c</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">s</mi> </mrow> </mrow> <mrow> <mrow> <mi mathvariant="normal">A</mi> <mi mathvariant="normal">v</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">g</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">d</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span>----------(2)</p><p>On substituting the values in the above equation:</p><p>1 mol =<span contenteditable="false"> <math> <mfrac> <mrow> <mrow> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">b</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">f</mi> <mi mathvariant="normal"> </mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">c</mi> <mi mathvariant="normal">u</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">s</mi> </mrow> </mrow> <mrow> <mrow> <mn>6.022</mn> <mo>×</mo> <mi mathvariant="normal"> </mi> <msup> <mrow> <mrow> <mn>10</mn> </mrow> </mrow> <mrow> <mrow> <mn>23</mn> </mrow> </mrow> </msup> <mi mathvariant="normal"> </mi> <mi mathvariant="normal"> </mi> </mrow> </mrow> </mfrac> </math> </span></p><p>Number of molecules = 1 <span contenteditable="false"> <math> <mo>×</mo> </math> </span>&nbsp;6.022 <span contenteditable="false"> <math> <mo>×</mo> </math> </span>10²³</p>

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