Answer:
electrons
Explanation:
The photoelectric effect occurs when electrons are emitted from metal when the metal is struck by light of certain frequencies.
Some of the applications of this effect include photomultipliers (which are a key component in spectroscopy instruments) and night vision devices.
Answer:
The relationship of the speed of sound, its frequency, and wavelength is the same as for all waves: vw = fλ, where vw is the speed of sound, f is its frequency, and λ is its wavelength. ... The more rigid (or less compressible) the medium, the faster the speed of sound
Explanation:
Some elements that are not abbreviated with one or two letters on the periodic table are Ununoctium (Uuo) and Ununtrium (Uut).
Answer:- 9.4 minutes.
Solution:- Radioactive decay obeys first order reaction kinetics and the equation used to solve this type of problems is:

where, k is decay constant and t is the time.
is the initial amount of the radioactive substance and N is the remaining amount.
Since the value of decay constant is not given, so we need to calculate it first from given half life by using the formula:

where
stands for half life.
Given half life is 3.0 minutes.
So, 

Let's plug in the values in the first order reaction equation and solve it for t.

It could also be written as:



k = 9.4 min
So, the radioactive substance would take 9.4 minutes to decay from 40.0 grams to 4.5 grams.