In a hydrocarbon's name, what does the suffix –yl indicate about the molecule?

there is a double carbon bond in the molecule.

there is a double hydrogen bond in the molecule.

there is a substituent in the molecule.

there is a triple carbon bond in the molecule.

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.