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
Boiling point<span> is the </span>temperature<span> at which the vapor pressure of the liquid equals the surrounding pressure.
Above boiling point point, liquid get converted into vapour.
Now, boiling point of water is 100 oC at room pressure. Room pressure is equal to 760 torr. Thus, at 100 oC, vapour pressure of water becomes equal to 760 torr.
Now, if external pressure is increased to 880 torr, more heat is to be supplied so that vapour pressure of water equals 880 torr.
So, at 880 torr, boiling point of water will be more than 100 oC. In present case, most like the boiling point of water is equal to 105 oC.
</span>
Answer:
the simplest answer is it loses the water (decahydrate) because it evaporates
Answer:
167.980.
Explanation:
Hello!
In this case, since additions involving the display of the result with the appropriate number of significant figures involve the solution of the system without looking at them:

Considering that 156.325 is significant to the thousandths and 11.65498 to the hundred thousandths, we infer that the result should be taken to the thousandths as well as 156.325; thus, we obtain:

Because the second decimal nine is rounded to ten and therefore the 7 is taken to 8.
Best regards!