After three half lives have passed, there would be only 12.5 percent of the original amount of a radioactive parent isotope that will remain. Half life is the time needed for a certain amount of a substance to be half its initial amount. It is a common term used in nuclear chemistry describing how fast radioactive substances undergo decay. One half life would correspond to only 50% would be left. Two half lives would be 25% only of the original value. Three half lives would be 12.5%. Four half lives would be 6.25% of the initial value. So on and so forth.
Answer:
A.) 1
Explanation:
Propane only exists in one conformation. It does not have enough carbons to form branches, and there are only hydrogens attached to each carbon. Furthermore, there is no way to twist the carbon or change its orientation (ex. cis- and trans-) to result in a different structure of propane. There is no other way to represent the molecule without drawing a different molecule.
The rows in the top third - This group consists of elements like Sodium, Magnesium, Potassium and Calcium on the right and Chlorine, Carbon, Nitrogen and Oxygen on the left.
Sodium and Chlorine are components of salt, a very important compound of our blood, essential for transferring electrical signals from the brain to the rest of the body and vice versa. Calcium is the building block of our bones, while Magnesium and potassium ensure proper functioning of our organs.
Answer:
13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.
Explanation:
Length of the base = l
Width of the base = w
Height of the pyramid = h
Volume of the pyramid = 
We have:
Rate at which water is filled in cube = 
Square based pyramid:
l = 6 cm, w = 6 cm, h = 13 cm
Volume of the square based pyramid = V





Differentiating V with respect to dt:




Putting, h = 4 cm


13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.
Group 17 is the most readily reduced elements on the periodic table, meaning that they are so close to being a stable elements, only missing 1 electron to complete their valance electron shell. Thus they will essentially react with anything to get that last electron!
Group 1 elements are extremely reactive because they are the most readily oxidized, they are very close to reaching stability by giving up only 1 electron. Thus they will react with almost anything to give up their electron.