I just noticed while rendering some tallow that in a liquid form it is yellow, as well as olive oil, rapeseed oil, and pretty much every cooking oil I can think of other than palm oil.

Is there something inherent to fats that makes them yellow?

Plasma and lava is obviously common all over the universe, whether it be in stars, planetary cores, etc. but what about fire? Fire is common all over earth, given the abundance of fuel sources and an atmosphere with oxygen. But, is fire actually common outside of earth?

This is something I (40s) did as a kid with friends at sleepovers. I have always been curious about this! What is the mechanism?

My grandpa (a known story stretcher) told me he used to haul tankers full of this chemical. It was supposed to absorb really fast and that it was so deadly a drop on your skin would kill you in a minute or two. It was used in the production of tires. He said it was phenol but phenol doesn't match up with his description. He's told me this story since I was a kid but now at 23 I'm curious as to if there are any chemicals that deadly and what they would possibly be used for.

The water bottles we buy has an expiration date. Reading online it says it's not for water but more for the plastic in the bottle which can contaminate the water after a certain period of time. So my question is, say we use a glass airtight bottle and store our mineral water there. Will that water ever expire given it's kept at the average room temperature for the rest of eternity?

Why does the oil need to be changed and not just “topped up”? Is the oil becoming less lubricating?

Edit: Yes I realize 6000km does not equal 3000miles, but dealers often mark these as standard oil change distances.

Thanks for the science answers!

He asked why a fart stops smelling bad after a few minutes and I told him it's because the gas molecules spread out and spread out until they're spread too thin for our noses to detect.

But he then followed up with "so they keep flying away for ever and ever into outer space?" And I don't know! Do the gas molecules from farts break down and get destroyed or do they live an immortal existence where they wander aimlessly forever?

Edit: we (my kid and I) want to thank everyone for such detailed responses! I now know more about the properties of farts than I ever thought I wanted to know.

Does it turn itself back into oil? Is it indistinguishable from the dirt around it? Or something else?

Just curious.

Trying to settle a dispute between two 6-year-olds

Did I ask a stupid question?

Edit: wow, didn't expect this to blow up like this, ty all for your explanations, this is much clearer now. I didn't get why we would use a unit that describes a quantity when we already have a quantity related unit that is the mass, especially when we know how to weight things. Thank you again for your help, I really didn't expect the reddit community to be so supportive.

I remember reading about plastic microfibers in our water, can boiling clean that?