<u>Answer:</u> The temperature to which the gas in the syringe must be heated is 720.5 K
<u>Explanation:</u>
To calculate the volume when temperature and pressure has changed, we use the equation given by combined gas law.
The equation follows:
where,
are the initial pressure, volume and temperature of the gas
are the final pressure, volume and temperature of the gas
We are given:
Putting values in above equation, we get:
Hence, the temperature to which the gas in the syringe must be heated is 720.5 K
Answer: The space occupied by the gas at 400 torr and 
is 250 mL.
Explanation:
Given: 
= 250 mL, 
= 800 torr, 
, 
= 400 torr, 
Formula used is as follows.
Substitute the values into above formula as follows.
Thus, we can conclude that space occupied by the gas at 400 torr and is 250 mL.
An exponential decay law has the general form: A = Ao * e ^ (-kt) =>
A/Ao = e^(-kt)
Half-life time => A/Ao = 1/2, and t = 4.5 min
=> 1/2 = e^(-k*4.5) => ln(2) = 4.5k => k = ln(2) / 4.5 ≈ 0.154
Now replace the value of k, Ao = 28g and t = 7 min to find how many grams of Thalium-207 will remain:
A = Ao e ^ (-kt) = 28 g * e ^( -0.154 * 7) = 9.5 g
Answer 9.5 g.
Answer: Molecular mass of the phenol is 94g/mol.
Explanation:
Phenol is an active ingredient in some oral anesthetics used in sore throat sprays.It is used as anesthetics to cure minor sour throat pain , minor mouth irritations etc.
For Example : Cramex , Chloraseptic sprays contains phenol as an active ingredient.
Phenol has a molecular formula of 
Molecular mass of the phenol = 6(mass of carbon)+5(mass of hydrogen)+1(mass of oxygen)+1(mass of hydrogen) = 6(12)+5(1)+1(16)+(1) = 94 g/mol
The answer is statement #3.
