Which of the following is correctly abbreviated si unit describing the mass of an object? a) kg b) mol c) m d) m

A) kg is your answer

"Mass" is weight without gravity, and so the SI unit would also use the weight measurement. (You solve by dividing the force of gravity from the total weight to get mass.)

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the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .