Answer : The volume of liquid is 420 mL.
Explanation :
Density : The mass per unit volume of a substance is known as density.
Formula used:

As we are given:
Density of mercury = 13.5 g/mL
Mass = 12.5 pounds
First we have to convert mass of sample from pound to gram.
Conversion used:
As, 1 pound = 453.6 g
So, 12.5 pounds = 453.6 × 12.5 g = 5670 g
Now we have to calculate the volume of liquid.

Now putting all the given values in this formula, we get:

Volume = 420 mL
Therefore, the volume of liquid is 420 mL.
The answer is D) a neutron.
When we say an atom's mass is, like 5 atomic mass units actually we are saying that the total number of the neutrons and protons in its nucleus is 5.
The mass of a neutron and a proton is each one atomic mass unit.
Mass of a neutron is approximately 1 atomic mass unit.
Answer: 
Explanation: 1 gram is equal to 1000 Milligrams so

Since you go straight across its just multiplication so 0.00200x1000=200mg
To answer it in scientific notation it should just be
mg
Answer:
we will use the Clausius-Clapeyron equation to estimate the vapour pressures of the boiling ethanol at sea level pressure of 760mmHg:
ln (P2/P1) =
-
)
where
P1 and P2 are the vapour pressures at temperatures T1 and T2
Δ
vapH = the enthalpy of vaporization of the ETHANOL
R = the Universal Gas Constant
In this problem,
P
1
=
100 mmHg
; T
1
=
34.7 °C
=
307.07 K
P
2
=
760mmHg
T
2
=T⁻²=?
Δ
vap
H
=
38.6 kJ/mol
R
=
0.008314 kJ⋅K
-1
mol
-1
ln
(
760/10)=(0.00325 - T⁻²) (38.6kJ⋅mol-1
/0.008314
)
0.0004368=(0.00325 - T⁻²)
T⁻²=0.002813
T² = 355.47K
4 is correct for this one