4. A
because PbCl2 is an ionic compound and it's solid, so it's a substance.
It cannot be mixture, because it's a pure molecule.
5. D
despite that both substances are gases, colorless they are different molecules, so they should have different either chemical and physical properties
6. C
this substance made from W atoms and others are made from molecules
Explanation:
The given data is as follows.
P = 3 atm
= 
= 
= 9 L = 
(as 1 L = 0.001 
),
= 15 L = 
Heat energy = 800 J
As relation between work, pressure and change in volume is as follows.
W = 
or, W = 
Therefore, putting the given values into the above formula as follows.
W =
= 
= 1823.85 Nm
or, = 1823.85 J
As internal energy of the gas 
is as follows.
= Q - W
= 800 J - 1823.85 J
= -1023.85 J
Thus, we can conclude that the internal energy change of the given gas is -1023.85 J.
Commensalism is the relation ship between two species where one of the species is being benefited while the other is not benefited and not even harmed.
It is a type of symbiosis
the correct answer is
A) Birds feed off the insects that are stirred up from the grasses as cattle move through.
There are a few things you can do to make slime less sticky. You can either:
1) add a bit of baking soda (one to three tea spoons depending on how big it is, for the one that you show I would say one should be enough)
2)You can place it in hot water and squish the water out of it before placing it in cold water and then drying it out a bit with a towel. Don't forget to knead it a bit so it stays smooth and not too hard.
B , because some organelles located in plant cells are not present in the animal cell
