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1. Some basic concept of chemistry — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistry1. Some basic concept of chemistry1 Mark
MCQ
Suppose the elements $X$ and $Y$ combine to form two compounds $XY_2$ and $X_3Y_2.$ When $0.1$ mole of $XY_2$ weighs $10\ g$ and $0.05$ mole of $X_3Y_2$ weighs $9\ g,$ the atomic weights of $X$ and $Y$ are
  • ✓
    $40, 30$
  • B
    $60, 40$
  • C
    $20, 30$
  • D
    $30, 20$
✓

Answer

Correct option: A.
$40, 30$
a
For $X Y_{2}$

$\because 0.1 \mathrm{mole}$

$X Y_{2} \equiv 10 g \therefore 1 \mathrm{mole}$

$X Y_{2} \equiv 100 g=X+2 Y=100 \ldots (1)$

For $X_{3} Y_{2}$

$\because 0.05$ mole

$X_{3} Y_{2}$

$\because 9 g$

$\therefore 1$ mole $X_{3} Y_{2} \equiv 180 g$

$3X+2Y=180\dots (2)$

On solving $(1)$ and $(2)$, $X=40$ And $Y=30$

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