The vapors of some chemicals used in the chemistry laboratory, especially isocyanates, can react and bond the contact lens to the eye.
(FYI - the family of isocyanates include Superglue..I wouldn't want to have been the person who discovered this unfortunate reaction!)
Answer:
i. Lead nitrate:
2Pb (NO3)2 Δ= 2PbO+4NO2+O2
ii. Potassium chlorate:
2KClO3 → 2KCl + 3O2↑
iii. clacium carbonate:
CaCO3 + 2HCl -> CaCl2 + CO2 + H2O
iv. cupric carbonate :
CuCO3 → CuO + CO2↑
Hope this helped
All the best!!
The change in energy is is known as work-energy