Answer:- choice d is correct. Sr<Ca<Be .
Explanations:- Br, Ca, and Sr are all elements of same group as they all have 2 valence electrons. As we move down in a group, a new shell is being added that increases the size of the atom. As the size of an atom increases, it is easy to remove the electron from it's outer most shell in it's gaseous state. Since, Be is above Ca and Ca is above Sr. The size increases in the order, Be < Ca < Sr. It means Be is the smallest one of them and so it's hard to remove from it's outer most shell and hence it's ionization energy is higher.
Sr is largest one in these three elements and so it's easy to remove outer most electron from it that means the ionization energy is least. Ca is between Be and Sr.
So, an increasing order of ionization energy is Sr<Ca<Be . Choice D is correct.
If this is for homework then eat lots of bacon.
Hello!
How many molecules are in 30 liters of methane (CH4) at STP ?
We have the following information:
Knowing that by Avogadro's Law for each mole of substance we have 6.02 * 10²³ molecules, it is known that in STP (Standard Temperature and Pressure) one mole of any gas equals 22.4 L, then:
22.4 L ----------------- 6.02*10²³ molecules
30 L -------------------- y molecules
multiply the means by the extremes
Answer:
8.0625*10²³ molecules of methane
________________________
Answer:
A. 29.9
Explanation:
- An element can have differing numbers of neutrons in its nucleus, but it always has the same number of protons. The versions of an element with different neutrons have different masses and are called isotopes.
- The average atomic mass for an element is calculated by summing the masses of the element’s isotopes, each multiplied by its natural abundance on Earth.
<em>Average atomic mass of P = ∑(Isotope mass)(its abundance)</em>
∴ Average atomic mass of P = (P-29 mass)(its abundance) + (P-30 mass)(its abundance) + (P-31 mass)(its abundance) + (P-33 mass)(its abundance)
<em>Abundance of isotope = % of the isotope / 100.</em>
<em>∴ Average atomic mass of P =</em> (29)(0.327) + (30)(0.4803) + (31)(0.184) + (33)(0.0087) = <em>29.88 a.m.u ≅ 29.9 a.m.u.</em>
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<em>So, the right choice is: A. 29.9</em>