MCQ
Given are two statements one is labelled as Assertion $A$ and other is labelled as Reason $R$.

Assertion $A$ :Magnesium can reduce $Al _{2} O _{3}$ at a temperature below $1350^{\circ} C$, while above $1350^{\circ} C$ aluminium can reduce $MgO$.

Reason $R$ : The melting and boiling points of magnesium are lower than those of aluminium.

In light of the above statements. choose most appropriate answer from the options given below

  • A
    Both $A$ and $R$ are correct. and $R$ is correct explanation of $A$.
  • Both $A$ and $R$ are correct. but $R$ is NOT the correct explanation of $A$.
  • C
    $A$ is correct $R$ is not correct.
  • D
    $A$ is not correct. $R$ is correct.

Answer

Correct option: B.
Both $A$ and $R$ are correct. but $R$ is NOT the correct explanation of $A$.
b
From Ellingham diagram given in NCERT, it can be seen that $Mg , MgO$ line crosses $Al , Al _{2} O _{3}$ line after $1350^{\circ} C$ hence assertion is true.

Yes, Mg have lower MP and BP than aluminium but it does not explain the above fact.

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