1. what is the colour of feso4.7h20 crystals? how does this colour change upon heating? give balanced
chemical equation for the changes.
2. a. what are redox reactions?
b. why is the reaction between mno2 and hcl a
redox reaction?
c. identify the substance oxidized and the
substance reduced in the above reaction.
3. balance the chemical equation: -
fe(s) + h2o(g)=fe3o4(s) + h2(g)
4. explain why:
a)respiration is an exothermic reaction.
b)all decomposition reactions are endothermic
reactions.

1. What is the colour of FeSO4.7H20 crystals?How does this colour change upon heating?

Melanterite or FeSO4.7H20 is green in color
2FeSO4 ---> Fe2O3 + SO2 + SO3

2. a. What are redox reactions?
It is a type of chemical reaction that involves a transfer of electrons between two species. 

b.Why is the reaction between MnO2 and HCl a 
redox reaction?
Because there are atoms that are reduced and are oxidized.

c.Identify the substance oxidized and the 
substance reduced in the above reaction.

MnO2 + 4 HCl ---> MnCl2 + 2H2O + Cl2
Mn was reduced and Cl was oxidized

Any photo? or something

Olá. porque a reação na temperatura é muito rapida a do copo : )