Answer:
3 elements
Calcium,oxygen and hydrogen
Location,types that is your answer for this one hope i helped
Answer:
b) sharpening a pencil
Explanation:
If you melt lead, boil water, or dissolve sugar in water, you can return all of them back to their original state. If you sharpen a pencil, you can't reattach the shavings as they were originally.
Answer:
Brown color of the solution decreases
Explanation:
is brown in color whereas 
is colorless.
Equilibrium reaction between and is as follows:
As per the Le Chatelier's principle, if pressure of a equilibrium is increased, the equilibrium will shift in the direction having fewer no. of moles of gases.
In the given equilibrium, side has more no. of moles. So on increasing pressure, equilibrium will shift towards the side of or more formation of will take place.
Therefore, more will decompose that will decrease the brown color of the solution as is colorless.
I think its density is 850kg/m^3
