What is chemical shift?

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.

What is the percentage of hydrogen in c2h4