Answer:
Correct answers are B and F.
Explanation:
Inside the test tube after a certain time, the pressure inside of the test tube must be equal to the atmospheric pressure, the hydrogen displaces the water inside the tube until the pressure is the same with the atmosphere.
The hydrogen pressure inside the tube must be lower than the atmospheric pressure because otherwise the water inside it would go out until it reaches the atmosphere pressure. The atmospheric pressure is equal to the addition of the hydrogen and water pressures.
The clean air act of 1990 was important because it helped reduce pollution and keep the enviornment safe. The act organized the idea's of 'safe' in regards to the ozone layer and also the air (generally). This meant that the amount of acid rainfall was controlled. It set rules and policies regarding polluting. Basically, people needed to wake up and think about the enviornment. Companies, people, and even communities were all now responsible for keeping what they breathe (air) clean.
Does this explain it pretty well? If not, please feel free to comment! Thanks for being part of Brainly. :)
Answer:
The Answer is B. Destructive Interference
Explanation:
Answer: at relatively low temperatures.
Explanation:
According to Gibbs equation;

= Gibb's free energy change
= enthalpy change
T = temperature
= entropy change
A reaction is spontaneous when
= Gibb's free energy change is negative.
Thus 

Thus the reaction is spontaneous or
is negative only when 
Thus the reaction is spontaneous at relatively low temperatures
Answer: D. The number of molecules having Er or greater doubles.
Explanation: As the temperature increases from 20°C to 30°C, the number of molecules with maximum energy decreases, but the number of effective collisions which result into the formation of product doubles.
This is due to doubling of molecules which possess energy equal to or greater than
which means now double number of molecules will be able to cross the energy barrier and hence the formation of product increases and hence the rate increases to double.