How can you observe colourless gas?

How long can a black holes exist? Do you have talc free powders in estee lauder? Is it safe to mix orange juice and soy sauce? Can you magnetize also an iron nail by stroking? Is there oxogyn on the sun? Where did Grover grow up? Identify the characteristic of a solid? What factors affect capillarity? Why do cells need to die? Is it 100 percent sure that a blue eyed man and green eyed women cannot have a brown eyed child? What time is it in Japan when it is 3 pm in Ontario Canada? What are two functions of the does cell membrane have? What is the most common rock that is mined using a quarry? Why don't we have earthquakes in Michigan? What is a systematic diagram? What is the name of the groups of organs working together to perform particular jobs in the body? Why when women get fixed or tubes tied do they still minstrate unlike when you get your cat or dog fixed? Why is darwin's theory of natural selection referred to as gradualism? Can microwaves be used in space? What is the layer of black pigment cells which absorbs light rays called?