Answer:
C. I, III , IV
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.
Answer:
8.0 × 10²¹ atoms contain 1.33 × 10⁻² moles.
Explanation:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
18 g of water = 1 mole = 6.022 × 10²³ molecules of water
1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen
Given data:
Number of atoms = 8.0 × 10²¹ atoms
Number of moles = ?
Solution:
One mole of Cu = 6.022 × 10²³ atoms
For 8.0 × 10²¹ atoms:
(1 mol / 6.022 × 10²³ atoms)×8.0 × 10²¹ atoms
1.33 × 10⁻² moles
So, 8.0 × 10²¹ atoms contain 1.33 × 10⁻² moles.
Answer:
Atoms are not created or destroyed by chemical reactions. Also, matter is neither created nor destroyed, it just changes form. Matter cannot be created or destroyed. ... The Law of Conservation of Mass states that in a chemical reaction the total mass of reactants is equal to the total mass of products.
Explanation:
According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants. The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such the amount of gas consumed or produced during a reaction.
For example, when wood burns, the mass of the soot, ashes, and gases equals the original mass of the charcoal and the oxygen when it first reacted. So the mass of the product equals the mass of the reactant.
