JEE Main 2022 · 28 Jun · Shift 1 · Chemistry Q64

ChemistrySingle correct+4 / -1Question 64 of 90

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

Assertion A : Magnesium can reduce $\mathrm{Al_2O_3}$ at a temperature below 1350°C, while above 1350°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 :

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.

A is correct R is not correct.

A is not correct, R is correct.

Answer and worked solution

Official answer: B

Assertion. On the Ellingham diagram the MgO and $\mathrm{Al_2O_3}$ lines cross near 1350 °C: true.

Reason. Mg melts and boils at lower temperatures than Al: true. NTA's key does not treat it as the explanation of the crossover.

(B)

Topics:Extraction and thermodynamics (Ellingham)

JEE Main 2022 · 28 Jun · Shift 1, Chemistry question 64