MCQ
Consider the following data

       Element      Atomic mass
       $A$      $12.01$
      $B$      $35.5$

$A$ and $B$ combine to form new substance $X$ . If $4\,moles$ of $B$ combine with $1\,mole$ of $A$ to give $1\,mole$ of $X,$ then weight of one mole of $X$ is ........... $\mathrm{g}$

  • $154$
  • B
    $74$
  • C
    $47.5$
  • D
    $166$

Answer

Correct option: A.
$154$
a
$4 B+A \rightarrow X$

$X$ is $A B_{4}$

weight of $1$ mol of $X$ is weight of $1$ mol of $AB$ $_{4}$

weight of $1 \mathrm{mol}$ of $\mathrm{AB}_{4}=1 \times 12.01+4(35.5)$

$=154 \mathrm{g}$

weight of $1$ mol $\mathrm{X}=154 \mathrm{g}$

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