HEINZYellow Mustard, 20 oz/566 g - 1 Bottle

I know this is a weird question, but I am a science teacher and need some of these for a lab. Do these float in water?

Is there an expiration date?

Is this for sure 500 ct. mustard packets? The description says relish, but everything else says mustard. Can anyone tell me?

.25 oz dijon packets for under $0.07?