Not sure, but I would guess it's due to environmental factors, like heat, and imperfections in the metal. Just an educated guess, though.
Answer: B. Can provide humans with energy forever
Explanation: The warm air rises and cooler air rushes in to take its place. The moving air is wind. As long as the sun shines, there will be winds on the Earth. We will never run out of wind energy.
Copper II oxide is a compound.
Due to hydrogen bonding there is a formation of cage like structure called lattice in ice due to which <span> density of ice is less than that of water. Moreover, it is a known fact that density of water is maximum at 4°C.</span>
Answer:
Explanation: A yellow precipitate o lead iodide is formed. see equation of reaction below: 
→ 
Th PbI2 is the insoluble yellow precipitate
