Of Uranium-235 remains after 2.8 x 10^9 years, what was the original mass of the sample of Uranium-235? The half-life of Uranium-235 is 7.0 x 10^8 years. Uranium-232 has a half life of 68.8 years.
Answer:
( B) They all have their valence electrons in the same type of subshell.
Explanation:
With each period, a new shell is added to the atom.
Further, the groups are classified based on the type of subshell the last electron enters and number of valence electrons.
For all elements of same group, the last electron enters the same type of subshell.
Say, for group 1, last electron enters s orbital and they have 1 valence elctron.
for group 17, last electron enters p orbital and they have 7 valence electrons.
(A) and (D) are wrong because, energy level of the valence electrons is determined by the principle quantum number n and l and not by the type of subshell(only l) they enter.
(C) if the valence electron enters p orbital, then the elements will be placed in the p- block.
Answer:
the attraction water molecules have to other surfaces
Explanation:
Adhesion is defined as the attractive forces between unlike substances, e.g water moving up a capillary tube.
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another(Wikipedia).
So, what we mean by adhesion in this context, is the attraction water molecules to other surfaces.
You need the solubility of the LiCl in water at 20°C.
The solubilities are shown in tables. Many books contain those tables. You have to make sure that the solubility is shown in the same solvent and at the same temperature that you are going to prepare the solution.
In this case the solubility of LiCl in water at 20°C is 83.05 g of LiCl in 100 g of H2O. Check if your book and your teacher work with the same value.
Using 8.05 g LiCl / 100 g of water you get:
300 g of water * 83.05 g LiCl / 100 g of water = 249.15 g of LiCl.
Answer: 249.15 g of LiCl