A chemical property refers to that which cannot be physically determined. From the choices given above, the chemical property of one of the student's materials is the reactivity of the copper strip. Thus, the answer to this item is letter B.
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: 1.12 Liters
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
1 mol of 
occupy = 22.4 L
Thus 0.05 mol of will occupy = 
Answer:
- The room mantained at a lower temperature will contain more air molecules.
Explanation:
1) Since the two rooms are <em>connected by an open door</em>, you assume pressure equilibrium: the pressure on the two rooms is the same.
2) Since you consider <em>two equal size rooms</em>, both volumes are equal.
3) Assuming ideal gas behavior, pressure (P), temperature (T), volume (V) and number of moles (n) are related by the equation PV = nRT
4) Naming T₁ the lower temperature, T₂ the higher temperature, n₁ the number of moles of air in the room at lower temperature, and n₂ the number of moles of air in the room at higher temperature, you get:
- n₁ T₁ = n₂ T₂, or n₁ / n₂ = T₂ / T₁
5) That means that the amount of molecules (number of moles) is inversely related to the temperature: the higher the temperature the lower the number of moles, and the lower the temperature the greater the number of moles.
Hence, the answer is that <em>the room that contains more air molecules is the room mantained at a lower temperature.</em>
Answer:
Russia es el mejor pais? Vladimir Putin, es el mejor presidente del mundo
