The proposed mechanism for a reaction is: Step 1: A + B X (fast) Step 2: X + C Y (slow) Step 3: Y D (fast) What is the overall reaction? A. A + B + C D B. A + X Y + D C. A + B Y D. A + Y D

A. A + B + C --> D

Explanation:

Step 1: A + B --> X (fast)

Step 2: X + C --> Y (slow)

Step 3: Y --> D (fast)

To obtain the overall reaction, we have to sum up the reactants and products of all step and eliminate the intermediates.

Reactants:

A + B + X + C + Y

Products:

X + Y + D

So we have;

A + B + X + C + Y  --> X + Y + D

Upon elimination of intermediates, we have;

A + B + C --> D

The correct option is A.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).