The answer is 40.
We can solve this by finding out the number of protons, and neutrons. Atomic number of an element means the number of protons in that element. So, the atom has 30 protons if the atomic number is 30.
On the other hand, mass number is the total number of protons and neutrons, but not electrons, because they're too light comparing to the other 2. Therefore, we can simply solve the number of neutrons in the atom by subtracting the number of protons from the mass number. 70 - 30 = 40.
Therfore, the number of neutrons is 40.
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Answer:</h3>
Lead-205 (Pb-205)
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Explanation:</h3>
<u>We are given;</u>
We are supposed to identify its product after an alpha decay;
- Polonium-209 has a mass number of 209 and an atomic number of 84.
- When an element undergoes an alpha decay, the mass number decreases by 4 while the atomic number decreases by 2.
- Therefore, when Po-209 undergoes alpha decay it results to the formation of a product with a mass number of 205 and atomic number of 82.
- The product from this decay is Pb-205, because Pb-205 has a mass number of 205 and atomic number 82.
- The equation for the decay is;
²⁰⁹₈₄Po → ²⁰⁵₈₂Pb + ⁴₂He
- Note; An alpha particle is represented by a helium nucleus, ⁴₂He.
The freezing point depression is a colligative property which means that it is proportional to the number of particles dissolved.
The number of particles dissolved depends on the dissociation constant of the solutes, when theyt are ionic substances.
If you have equal concentrations of two solutions on of which is of a ionic compound and the other not, then the ionic soluton will contain more particles (ions) and so its freezing point will decrease more (will be lower at end).
In this way you can compare the freezing points of solutions of KCl, Ch3OH, Ba(OH)2, and CH3COOH, which have the same concentration.
As I explained the solution that produces more ions will exhibit the greates depression of the freezing point, leading to the lowest freezing point.
In this case, Ba(OH)2 will produce 3 iones, while KCl will produce 2, CH3OH will not dissociate into ions, and CH3COOH will have a low dissociation constant.
Answer: Then, you can predict that Ba(OH)2 solution has the lowest freezing point.
Answer: The increase in solubility or the rate of dissolving process of a gaseous solute in a liquid solvent is due to following:
- Increasing agitation
- Increasing temperature
- Increasing solute's partial pressure over the solvent
- Increasing solute's surface area
Explanation:
When agitation is increased then there will occur an increase in kinetic energy of the molecules of a substance. As a result, more number of collisions will take place due to which more amount of solute will dissolve into the solvent.
Similarly, increasing the temperature will further increase the kinetic energy of molecules. Hence, this will lead to more solubility of gaseous solute into the liquid solvent.
As solubility of a gas is directly proportional to the pressure of the gas above surface of the solution. So, an increase in solute's partial pressure over solvent will also lead to an increase in solubility of gaseous solute into liquid solvent.
When surface area of solute is increased then there will be more solute particles available for reaction. Hence, more collisions will take place. As a result, rate of reaction is more due to which there will be an increase in solubility.
Thus, we can conclude that the increase in solubility or the rate of dissolving process of a gaseous solute in a liquid solvent is due to following:
- Increasing agitation
- Increasing temperature
- Increasing solute's partial pressure over the solvent
- Increasing solute's surface area
