Answer: 8.7 grams
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
As oxygen is in excess, Aluminium is the limiting reagent and limits the formation of products.
According to stoichiometry:
4 moles of aluminium give = 2 moles of 
Thus 0.17 moles of aluminium give=
Mass of 
Thus the mass of is 8.7 grams
<span>C. polar bonds and asymmetrical structure
If the molecule contains polar bonds but it has a symmetrical structure, the polar bonds will cancel each other out so the overall molecule will be non-polar.
On the other hand, if the molecule contains polar bonds but has an asymmetrical structure, then the polar bonds won't cancel each other out, so the overall molecule ends up being polar.
</span>
Using the mass/volume percentage method for percentages of the solution, you simply divide the grams of solute by the volume of the solution and multiply by 100 to get your percentage.
(75.0g/250mL)•100 = 30.0% solute
The answer is D I hope this helps you !
Answer: B (Items with densities lower than water will sink due to surface tension)
Explanation:
Surface tension is an intermolecular force exerted on the surface of water making it like a stretch elastic skin. Surface tension enables items with lesser densities than water, to float and slide on a water surface. Examples insects, leaves, paper etc
According to Archimedes principle an object denser than the fluid will sink. While objects less dense than the fluid will float.
Answer is (B) is false because items with densities higher then water will sink due to surface tension
