Please Help: SCIENCE STUDY GUIDE QUESTIONS?

Question

I need help with these questions. Answer as many as you can.

1) Gases do not form liquids, unless the temperature is lowered, because of the
a) extremely small size of the gas particles
b)relatively slow motion of the gas particles
c)weak attractive forces between particles
d)presence of repulsion forces between particles.

2)One way for a balloon to rise in air is to
a)heat the air inside the balloon
b)increase the pressure of the air inside the balloon
c)choose a gas with a weight less than the air it displaces
d)choose a gas with a density greater that the air it displaces

3) Which of the following gases would you expect to have the greates lifting power?
a)hydrogen
b)oxygen
c)astatine
d)hydrogen fluoride

Answer 1

1) a) the van der Waals forces attracting gas molecules/atoms together are small. c) Weak attractive forces, because of the above answer, d) Gas atoms and molecules are surrounded by negatively-charged electrons around their perpheries. Like charges repel, so there is a mutual repuilsion among gas molecules/atoms.

2) a) Heating makes the gas less dense and so causes the balloon to rise. c) Choose a gas less dense than air, like hydrogen or helium.

3) Greatest lifting power would be a) H2, because the molecular weight of hydrogen is 2, whereas the effective molecular weight of air is 28.5. d) HF, comes in second, because the molecular weight is 20. Oxygen (32) and astatine (At2) (420) would float like a lead balloon.

Answer 2

a million) on condition that cotton is extremely easy, equivalent hundreds of sand and cotton will effect in the quantity of the cotton being plenty plenty greater beneficial. think of roughly how heavy a cotton ball is in comparison to a ball of sand. have you ever been burried in sand on the coastline? It places rigidity on your chest. yet once you sleep under a ffuffy cotton blanket, its not heavy in any respect. so as that's why in case you have equivalent hundreds (basically weight) the volumes could be distinctive. 2) The temperature of water impacts how briskly sugar dissolves simply by fact simply by fact the temperature of the water rises, the fee of the sugar dissolving additionally rises. In different words, the better the temperature of the water is, the swifter it is going to dissolve. it is with the aid of the fact the water molecules are polar and harm aside the sugar crystals into smaller individual molecules while they stumble upon one yet another. once you warmth the water, the water molecules circulate around plenty swifter, increasing the prospect and velocity at which it bumps into sugar molecules. This makes the sugar dissolve swifter in heated water. desire that enables

Answer 3

1.d
2.a and c
3.a