Oxidation number of an atom is the charge that atom would have if the compound is composed of ions. In neutral substances that contains atoms of one element the oxidation number of an atom is zero. Thus atoms in O2, Ni2, and aluminium all have oxidation number of zero.
In this case, Ni2, the oxidation number of Ni atom is zero,
for NiO4-, assuming oxidation number of Ni is x
(x ×1) + (-2 × 4) = -1
x = + 7
Therefore, the oxidation number goes from 0 to +7
The reaction rate or rate of reaction is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time.
Reactions that happen quickly have a high rate of reaction. For example, the chemical weathering of rocks is a very slow reaction: it has a low rate of reaction. Explosions are very fast reactions: they have a high rate of reaction. Rate of reaction is an example of a compound measure.
Repeat trials multiple times
Answer:
According to avogadro's law, 1 mole of every substance contains avogadro's number 
of particles and weighs equal to its molecular mass.
To calculate the moles, we use the equation:
a. moles in 14.08 g of 
= 
molecules in 14.08 g of = 
b. moles in 17.75 g of NaCl = 
molecules in 17.75 g of 
= 
formula units 17.75 g of =
c. moles in 20.06 g of 
= 
formula units in 20.06 g of = 
The correct answer is C) A substance changes color when heated, but changes back when cooled. Hope this helps.
