I’m not sure if there was important information in the question before this one, but the answer based on the info I have is B.
The density of water is 1kg/L. Since the density of the block is less, it will float.
Boyle found that when the pressure of gas at a constant temperature is increased, the volume of the gas decreases. when the pressure of gas is decreased, the volume increases. this relationship between pressure and volume is called Boyle's law.
Answer: 0.055 moles of 
are produced by the reaction of 0.055 mol of ammonium perchlorate.
Explanation:
The balanced chemical reaction for decomposition of ammonium perchlorate is:
According to stoichiometry :
2 moles of 
produce = 2 moles of
Thus 0.055 moles of will produce =
of
Thus 0.055 moles of are produced by the reaction of 0.055mol of ammonium perchlorate.
There are 4 lone pairs of electrons present in the carbon dioxide molecule
