cold water is denser than hot water. The same is true of most other substances as well.
One for the hot water, one for the cold.
Are you talking about pipes under a slab here? If so you probably have a hot water line under the slab leaking that is heating the water in the cold line.
HOT rises COLD sinks
The hot water under the sink is typically on the left side.
2-3 usually. 1 each for hot and cold water and possibly a third for hot water going to dishwasher.
It sinks faster in hot water than warm or cold
When cold water is poured into hot water, it sinks because it is denser than the hot water. The cold water is heavier due to the molecules being closer together at a lower temperature, causing it to sink to the bottom. The hot water, which is less dense, rises to the top.
depending on what type of faucet you have sometimes you need to close both hot and cold angle stop valves under sink.
If hot water is coming out of the cold tap, it may be due to a plumbing issue where the hot and cold water lines are crossed. To fix this, you can check the plumbing connections under the sink and ensure the hot and cold water lines are properly connected to the correct taps. If the issue persists, you may need to consult a professional plumber to resolve the problem.
Because hot water heater breaker has tripped, or hot water heater has failed.
run it under hot water in the sink
They would be the stops under the sink for each of the cold and hot waters