1mol ------------ 3×6,02×10²³ oxygen atoms
x ------------ 2,55×10²⁴
x = 2,5×10²⁴ × 1mol / 3×6,02×10²³ ≈ 0,138*10 mol = 1,38mol
Answer:
a) Na
c) Na
b) Sr
d) Ca
Explanation:
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.
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.
When ice melts, the physicals state changes from solid to liquid. The energy or the heat required (q) required to change a unit mass (m) of a substance from solid to liquid is known as the enthalpy or heat of fusion (ΔHf). The variables; q, m and ΔHf are related as:
q = m * ΔHf
the mass of ice m = 65 g
the heat of fusion of water at 0C = ΔHf = 334 J/g
Therefore: q = 65 g * 334 J/g = 21710 J
Now:
4.184 J = 1 cal
which implies that: 21710 J = 1 cal * 21710 J/4.184 J = 5188.8 cal
Hence the heat required is 5188.8 cal or 5.2 Kcal (approx)
The States of Matter are classified into solid, liquid, and gas. Among these physical states, if we are going to refer to the water molecules, the one that would possess the greatest energy is gas. If you would take the energy of gas, this would become liquid. The answer is option C.
There are several information's already given in the question. Based on the information's provided, the answer can be easily deduced.
V1 = 25 ml
= 25/1000 liter
= 0.025 liter
V2 = 18 ml
= 18/1000 liter
= 0.018 liter
M2 = 1.0 M
M1 = ?
Then
M1V1 = M2V2
M1 = M2V2/V1
= (1 * 0.018)/0.025
= 0.72 M
From the above deduction, it can be easily concluded that the correct option among all the options that are given in the question is the first option or option "A". I hope that this is the answer that has actually come to your help.
