To solve this problem, we can simply calculate for the
dose by multiplying the volume of solution containing Selenium 75 and the
activity of the Selenium 75. That is:
dose = 4.1 mL * (45 μCi/mL)
dose = 184.5 μCi
Answer:
The mass of silicon in kilograms in Earth's crust is
.
Explanation:
Mass of Earth =
(1 ton= 2000 lb)
(1 lb =453.6 g)
1 ton = 2000 × 453.6 g =907,200 g
Mass of Earth =
Percentage of earth crust = 0.50%
Mass of earth crust = M
Percentage of the silicon in Earth's crust = 27.2 %
Mass of silicon in in Earth's crust = m
1000 g = 1 kg
The mass of silicon in kilograms in Earth's crust is.
Answer: 3.01 x 10^24 atoms
Explanation:
Based on Avogadro's law:
1 mole of any substance has 6.02 x 10^23 atoms
So, 1 mole of water = 6.02 x 10^23 atoms
5 moles of water = Z atoms
To get the value of Z, cross multiply
Z x 1 mole = (6.02 x 10^23 atoms x 5 moles)
Z•mole = 30.1 x 10^23 atoms•mole
Divide both sides by 1 mole
Z•mole/1 mole = 30.1 x 10^23 atoms•mole/ 1 mole
Z = 30.1 x 10^23 atoms
[Place the value of Z in standard form]
Z = 3.01 x 10^24 atoms
Thus, there are 3.01 x 10^24 atoms in 5 mole of water
Answer:
C. The first ionization energy decreases because the outermost
electron is farther from the nucleus.
Explanation:
Ionization energy trend along group:
As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.
As the size of atom increases the ionization energy from top to bottom also decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.
Ionization energy trend along period:
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.
Answer: A, C, E
Explanation: PLATO. all testable questions.
