Answer:

Explanation:
1 mole of any substance contains the same number of particles. The particles can vary (atoms, molecules, formula units), but there are always 6.022*10²³ particles. In this case, the particles are formula units of potassium nitrate or KNO₃.
Let's create a ratio.

Since we are trying to find the formula units in 0.250 moles, we multiply by that number.

The units of moles of potassium nitrate cancel.

The denominator of 1 can be ignored, so we can make a simple multiplication problem.


If we round to the nearest tenth, the 0 in the hundredth place tells us to leave the 5 in the tenth place.

0.250 moles of potassium nitrate is approximately equal to 1.5*10²³ formula units of potassium nitrate and choice B is correct.
The melting points of the compounds from the choices are listed below:
a. C25H52 -> +47 to +56 degrees celsius
b. Hg -> -38.83 degrees celsius
c. CaCl2 -> +772 degrees celsius
d. CuO -> +1326 degrees celsius
It is evident from the listed melting points above that mercury (Hg) has the lowest melting point. This is why mercury is liquid at room temperature.
Answer:J.J. Thomson, he was using a high-vacuum cathode-ray tube
Explanation:(I Googled it)
Answer:
noble gases Ithink this is the answrr
The answer is A.18 let me know if you want an explanation