Answer: The correct statements are:
- Objects “fall” toward the center of Earth.
- Objects accelerate at a rate of 9.8 m/s each second.
- Objects are pulled by Earth more strongly than they pull on Earth.
Explanation:
The gravity of the earth is the force which attracts the object to the center of the earth. When the any object with mass falls under the action of the gravity attains the acceleration of 9.8 
.
- Objects “fall” toward the center of Earth.
- Objects accelerate at a rate of 9.8 m/s each second.
- Objects are pulled by Earth more strongly than they pull on Earth.
Answer:
636 balloons
Explanation:
If we assume that helium gas follows an ideal gas behaviour, we can use the ideal gas law to solve this problem as follows:
- We consider two different states, the initial given by the conditions of the problem statement and the final, when the tank reaches atmospheric pressure and it's no longer able to fill balloons:
- To find out what would be this volume 2, we use the Boyle's Law:
- Now we find the available volume to fill the balloons by substracting both, volume 2 and volume 1:
- Finally, we determine the quantity of ballons by dividing that available volume between the volume of each ballon:
The answer for this one is a
Answer:
Explanation:
C = Allowable concentration = 1.1 mg/L
= Flow rate of river = 
= Discharge from plant = 
= Background concentration = 0.69 mg/L
= Maximum concentration that of the pollutant
The concentration of the mixture will be
The maximum concentration that of the pollutant (in mg/L) that can be safely discharged from the wastewater treatment plant is .
To solve this we assume
that the gas is an ideal gas. Then, we can use the ideal gas equation which is
expressed as PV = nRT. At a constant temperature and number of moles of the gas
the product of PV is equal to some constant. At another set of condition of
temperature, the constant is still the same. Calculations are as follows:
P1V1 =P2V2
P2 = P1 x V1 / V2
P2 = 2.0 x 1.5 / 3
<span>P2 = 1 atm</span>
