It depends on the context iorn is a transition metal so it can hold a charge from 1-8
Pioneer species are the first species to arrive in an area after succession (hope this helped because i dont know about climax communities)
Answer: The reaction is exothermic
The
value is negative.
Heat is a product.
Explanation:

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and
for the reaction comes out to be positive.
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and
for the reaction comes out to be negative.
The substances which are written on the left side of the arrow are reactants and the substances which are written on the right side of the arrow are products. Thus heat is a product.
An aldehyde is an organic compound containing a terminal carbonyl group (C = O). This functional group, consisting of a carbon atom bound to a hydrogen atom and an oxygen atom via double bond (the general formula: CHO) is called the aldehyde group. In a reaction of the addition of alcohol to the carbonyl group, it forms hemiacetals.
On the picture attached it is shown the reaction of alcohol addition to the carbonyl group with the major organic product <span>formed in the reaction.</span>