Answer:
Choice number two. The value of "X" in this equation should be constant for all elements across a period.
Explanation:
Electrons are negative while protons are positive. Electrons are attracted to the proton but repel each other.
Consider an atom where electrons occupy more than one energy level. Consider the Bohr Model for that atom. Protons in the nucleus attract the electrons towards the center of the atom. However, at the same time, electrons in the inner shell will repel the valence electrons. That creates an outward force that pushes the valence electrons away from the atom.
The two forces mostly balance each other, but the attraction is slightly stronger. As a result, the overall force on the valence electrons is attractive. The effective nuclear charge gives the number of protons required to produce an attraction of that strength if there was no repulsion at all.
The value of effective nuclear charge is approximately the same as atomic number minus the number of inner-shell electrons. Apparently, the "X" in this question stands for the number of inner-shell electrons.
By the Aufbau Principle, all spots in the inner shell must be filled before more electrons can be added. Additionally, atoms in the same period have the same number of inner shells. As a result, the number of inner-shell electrons will be the same for all atoms in each period. Hence, the value of "X" should stay (approximately) the same across each period.
Answer:
The accuracy can be improved by making sure no external force is applied, i.e the marbles should accelerate under gravity only during each trial.
Explanation:
Accuracy is a term used to describe the relationship between a measured value to the real value. When a measured value is accurate, it implies that there is little or no error in the value; thus it is equal to the real value or very close to it.
Since this experiment is to determine the speed with which the marble roll down the plane, they should ensure uniform acceleration through out the trials. The marbles should be allowed to move under the influence of gravity only without applying any external force.
Bonds breaking and bonds making occurs. Bonds breakind is often endotherminc because they require energy to break the bonds and bond making releases energy so itis exothermic.
B) the bacteria that live in the intestine of a rabbit
To find the freezing point, you use the following formula
fp solution= fp solvent - Δfp solution
fp solvent= 0 C (since the solvent was not stated, you can assume is water which freezing point is 0 degree celsius)
but first, we need to find the depression in freezing point (Δfp solution)
Δfp solution= Kf x i x m, where Kf is constant for the solvent, i is the number of particles produced by the solute and m is the molality of the solution.
Kf= 1.86 for water
i= 4 , becausethe solute breaks into 4 ions, K3PO4---> 3K+ + PO4-3
m= 2.60
Δfp solution= (1.86) (4) (2.60)= 19.3 C
fp solution= 0 - 19.3C=<span> -19.3C
</span>
for boiling point, we use a similar formula and way to solve it.
Δbp solution= bp solvent + Δbp solution
bp solvent= 100 C for water
to find the elevation boiling point (Δbp soln) is equal to:
Δbp solution= Kb x i x m
Kb= 0.512
i= 4
m= 2.60
Δbp solution= (0.512) (4) (2.60)= 5.32 C
bp solution= 100C + 5.32C= <span>105.32 C</span>
