Answer: E. Electron pair donor
Explanation:
According to Arrhenius concept, a base is defined as a substance which donates hydroxide ions 
when dissolved in water and an acid is defined as a substance which donates hydronium ions 
in water.
According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.
According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.
Hence, the correct statement is Lewis base is Electron pair donor.
You haven't included the list of choices that goes with the question, so it's
impossible for me to choose the correct one, or to help you choose it.
Regarding my ability to answer the question and collect the 5-point bounty,
I'm free to make up any phrase of my own that correctly describes an atom.
-- very very very very very very very tiny
-- includes even tinier particles, with electric charges
both positive and negative
-- smaller than the wavelength of visible light
If we define each of the systems that are given in the options we will have to:
Air conditioning is the air treatment that modifies its conditions to suit certain needs, i.e., the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioners are also responsible for controlling humidity in closed rooms.
Positive Pressurization is a pressure within a system that is greater than the surrounding environment. Consequently, if there is any leakage of the system with positive pressure, it will leave the surrounding environment. There is no temperature or humidity control here
Ventilation is done by artificially creating depressions or overpressures in air distribution ducts or building areas. The fans are mechanically responsible for increasing the volume flow of air in a system. Moisture is not controlled directly.
Therefore the correct answer is A.
Power = (energy) divided by (time)
Answer:
Explanation:
Time period, T = 50 μs = 50 x 10^-6 s
Frequency is defined as the number of oscillations or vibrations completed in one second.
The reciprocal of time period is called frequency.
f = 1 / T
f = 1 / (50 x 10^-6)
f = 20,000 Hz
Angular frequency, ω = 2 x π x f
ω = 2 x 3.14 x 20,000
ω = 125600 rad/s
