Answer:
a) 12/323
b) 8/233
Explanation:
a) The probability of a red ball being drawn is 12/38, or in a simplified fraction, 6/19. To find the probability that 3 are red you would multiply the probability of the fraction for each, except subtracting one from the total each time as the drawn is done without replacement. This is done as follows: 6/19 × 6/18 × 6/17= 12/323
b) The probability of drawing a blue ball is 8/38, or 4/19. To find that the first one is blue and the rest are red, the equation is done as follows: 4/19 × 6/18 × 6/17 = 8/233
(hopefully I did this right)
Answer:
Explanation:
To calculate the cell potential we use the relation:
Eº cell = Eº oxidation + Eº reduction
Now in order to determine which of the species is going to be oxidized, we have to remember that the more the value of the reduction potential is negative, the greater its tendency to be oxidized is. In electrochemistry we use the values of the reductions potential in the tables for simplicity because the only thing we need to do is change the sign of the reduction potential for the oxized species .
So the species that is going to be oxidized is the Aluminium, and therefore:
Eº cell = -( -1.66 V ) + 0.340 V = 5.06 V
Equally valid is to write the equation as:
Eº cell = Eº reduction for the reduced species - Eº reduction for the oxidized species
These two expressions are equivalent, choose the one you fell more comfortable but be careful with the signs.
Answer: Colligative properties are those properties of solutions that are dependent on the concentration of the solutes in the solution.
Colligative properties has to do with solutions, that is, solutes that are dissolved in solvents. Examples of colligative properties are: freezing point depression, vapour pressure lowering, boiling point elevation and osmotic pressure. Colligative properties do not depend on the identity of the solutes, this implies that the effect of colligative properties are uniform across all solutions. For example, the freezing point depression of any solution will depend on the concentration of solutes that are dissolve in solution.
He was credited with discovering the subatomic particle also known as the electron in 1897.
Answer:
<em>Option A. It was delivered by comets that crashed into Earth's surface.</em>
Explanation:
<em><u>Uranium (U) is a chemical element with atomic number 92.</u></em>
<em />
<em>For many years, a large number of scientists have been studying the abundance and origin of the isotopes of uranium in Earth</em>. <u>According to some theories, the Earth's uranium was produced in one or more supernovae</u> (an explosive brightening of a star), in wich, the main process consists in the rapid capture of neutrons by seed nuclei at great rates. <u>Another theory proposes that uranium is created during the merger of two neutron stars</u> (neutron stars are very dense), because, when such dense bodies come closer together the gravitational force cause them to merge, producing huge amounts of hevy metals like uranium.
<u><em>Many analyses have been made of the uranium in rocks of the Earth. These measurements shows that the abundance of uranium is bigger in the crust and upper mantle of the Earth</em></u>.
So, knowing that Earth's uranium was produced through one of these processes, <u><em>the best answer is option A, the uranium was delivered by comets that crashed into Earth's surface.</em></u>
Have a nice day!
