A reaction occurs via the following sequence of elementary steps. What is the reaction intermediate? 1st step: A + 2B → 2C
2nd step: 2C → D

C is the reaction intermediate.

Explanation:

A reaction intermediate is a molecular structure that is formed during the reaction but then is converted in the final products.

Usually, these reaction intermediates are unestable and, for that reason, the lifetime of these structures is low.

In the reaction, you can see in the first step C is produced, but also, in the second step reacts producing D. As is produced and, immediately consumed,

indium, and thallium have three electrons i think

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).