Answer : The time passed by the sample is, 
Explanation :
Half-life = 30.0 min
First we have to calculate the rate constant, we use the formula :
Now we have to calculate the time passed.
Expression for rate law for first order kinetics is given by:
where,
k = rate constant = 
t = time passed by the sample = ?
a = initial amount of the reactant = 4.5 mg
a - x = amount left after decay process =0.25 mg
Now put all the given values in above equation, we get
Therefore, the time passed by the sample is,
Answer:
D
Explanation:
I - You should account the mass of the weighing paper to reduce it from the total mass at the end of the process, having only the mass of the Silver Chloride.
II - The precipitation of the silve chloride will occur independently of the temperature, because the Kps of this salt is very low (Ksp = [Ag+] .[Cl-]).
III - Washing the precipitate will secure the purity of the final product, it won't allow any other contaminant to be in your precipitante which could change your final mass.
IV - You should heat you AgCl precipitate so it will be dry, because of that the mass you will obtain is only the mass of the weighing paper and the silver chloride and nothing else.
Answer:
e. reducing the pressure from 608 torr to 0.40 atm at constant temperature.
Explanation:
According to Boyle's law when a gas is at the same temperature and there is a mass in a closed container so the pressure and the volume changes in the opposite direction
So here the equation is
Now we choose the options
where,
Now applying these values to the above equation
So,
P1V1=P2V2
0.8 = 0.8
Hence, it is proved
Answer:
A source of electricity, a wire coil, and an iron core
Explanation:
An electromagnet has three critical components:
1. A source of electricity
This is often a battery.
It generates the electric current that produces the magnetic field.
2. A wire coil
The wire carries the electric current.
Stacking the wire into loops makes a stronger magnetic field.
The more loops in the coil, the stronger the field.
3. An iron core
An iron core greatly increases the strength of the magnetic field within it and at its ends.
Boyle's law of ideal gas: This law states that the volume of a gas is inversely proportional to its pressure at a constant temperature. Acc to this law we can write the relation of pressure and volume as:
That means:
From that equation we can calculate Volume of gas at a certain pressure:
P₁=Initial pressure
V₁=Initial volume
P₂=Final pressure
V₂= Final volume
Here P₁, initial pressure is given as 85.0 kPa
V₁, initial volume is given as 525 mL
P₂, final pressure is 65.0 kPa
so,
V_{2}=85\times 525\div 65
=686 mL
Volume of gas will be 686 mL.
