Answer:
1) Ca: [Ar]4s²
2) Pm: [Xe]6s²4f⁵
Explanation:
1) Ca:
Its atomic number is 20. So it has 20 protons and 20 electrons.
Since it is in the row (period) 4 the noble gas before it is Ar, and the electron configuration is that of Argon whose atomic number is 18.
So, you have two more electrons (20 - 18 = 2) to distribute.
Those two electrons go the the orbital 4s.
Finally, the electron configuration is [Ar] 4s².
2) Pm
The atomic number of Pm is 61, so it has 61 protons and 61 electrons.
Pm is in the row (period) 6. So, the noble gas before Pm is Xe.
The atomic number of Xe is 54.
Therefore, you have to distribute 61 - 54 = 7 electrons on the orbitals 6s and 4f.
The resultant distribution for Pm is: [Xe]6s² 4f⁵.
35 m/s = 210000 cm/min
35*600=210000
The answer is (2). If you recall Rutherford's gold foil experiment, remember that a stream of positively charged alpha particles were shot at a gold foil in the center of a detector ring. The important observation was that although most of the particles passed straight through the foil without being deflected, a tiny fraction of the alpha particles were deflected off the axis of the shot, and some were even deflected almost back to the point from which they were shot. The fact that some of the alpha particles were deflected indicated a positive charge (because same charges repel), and the fact that only a small fraction of the particles were deflected indicated that the positive charge was concentrated in a small area, probably residing at the center of the atom.
Correct Answer: Option C:<span> The equilibrium position will shift to the right toward the products.
Reason:
1) This problem is based on </span>Le Chatelier's principle. It is stated as '<em>any</em><span><em> changes in the temperature, volume, or concentration of a system will result in predictable and opposing changes in the system in order minimize this change and achieve a new equilibrium state.</em>'
2) In present case, the reaction involved is:
</span><span> CH3CO2H(aq) + H2O(l) ⇄ CH3CO2-(aq) + H3O+(l)
</span>Hence, when the concentration of acetic acid (reactant) is increased, the equilibrium will shift to right to minimize the effect of change in concentration of reactant.
