Answer:
The salt is Zn(NO3)2
When the residue is allowed to cool, its colour changes from yellow to white
The equation of the reaction is; 2Zn(NO3)2(s) --->2ZnO(s) + 4NO2(g) + O2(g)
Explanation:
Decomposition of Zn(NO3)2 is one of the routes by which ZnO is obtained. ZnO is a white insoluble powder which has a yellow colour when hot and a white colour when cold. It is an amphoteric substance used as a white pigment in paints and as a filler for rubber.
In a very pure form, it is used in cosmetic powders and creams as well as in medicinal ointments and lotions.
Also recall that NO2 is a brown gas and oxygen gas rekindles a glowing splint.
Answer:
A) 
Explanation:
m = Mass of water = 38.9
M = Molar mass of water = 18 g/mol
= Avogadro's number = 
The reaction of electrolysis would be

Number of moles of 

From the reaction it can be seen that 2 moles of
gives 1 mole of 
So, number of moles of
produced is

Number of molecules

So,
of oxygen is produced.
Answer:
Explanation:
Pb(NO3)2(aq) + 2NaCl(aq) ==> PbCl2(s) + 2NaNO3(aq)
NO3- mixes with everything at beginning levels.
PbCl2 doesn't mix at all in water. It becomes a ppte, which means it is solid form. Your teacher might prefer using PbCl2(ppte). I think I'd ask to make sure.
Touch can sense the texture, and you can see what color it is, but if your talking about chemical properties, I'd say smell, color, and heat can identify some chemicals.