This is a simple case of ratios. (1 mol)/(22.4 L)=(n mol)/(.025 L) Then we cross multiply and we get 22.4n=.025 We divide each side by 22.4 to find n=.001116 mol Then to convert the moles to atoms we multiply, and cross-cancel the units (.001116 mol)/1 xx (6.02 xx 10^23 atms)/(1 mol) and we have 6.72 xx 10^20 atoms. I've found the trick of cross-cancelling units to be a very effective mnemonic, it always makes sure you carry out the correct calculation to find the desired units.
the object will float for a few seconds and most likely fall back down because it still has a little bit of gravity attached or it would float a few inches up but not too high in the air where its out of reach
The wistle is coming from all the chemicals including the fire you use to light the firework and a chemcial reaction is occuring which is the sound that is made because of this
