Answer:
A
Explanation:
To label an element correctly using a combination of the symbol, mass number and atomic number furnishes some important information about the element.
We can obtain these information from the element provided that correct labeling of the element is presented. Firstly, after writing the symbol of the element, the atomic number is placed as a subscript on the left while the mass number of the atomic mass is placed as a superscript on the same left.
Looking at the question asked, we have the element symbol in the correct position as Ca, with 42 also in the correct position which is the mass number. The third number which is 20 is thus the atomic number of the element.
Answer:
2K +F₂→ 2KF
Explanation:
When we balance an equation, we are trying to ensure that the number of atoms of each element is the same on both sides of the arrow.
On the left side of the arrow, there is 1 K atom and 2 F atoms. On the right, there is 1 K and 1 F atom.
Since the number of K atoms is currently balanced, balance the number of F atoms.
K +F₂→ 2KF
Now, that the number of F atoms is balanced on both sides, check if the number of K atoms are balanced.
<u>Left</u>
K atoms: 1
F atoms: 2
<u>Right</u>
K atoms: 2
F atoms: 2
The number of K atoms is not balanced.
2K +F₂→ 2KF
<u>Left</u>
K atoms: 2
F atoms: 2
<u>Right</u>
K atoms: 2
F atoms: 2
The equation is now balanced.
Answer:
The answer to your question is Mg loses its valence electrons and acquire a positive charge (Mg⁺²).
Explanation:
Valence electrons are important for an element to attach to another one, metals lose these electrons while nonmetals gain electrons to complete the octet rule.
Magnesium is a metal that loses these electrons so when it becomes an ion Magnesium will have a positive charge Mg⁺².
Answer:
C. Scientists accepted the model at first but later rejected it.
Explanation:
Scientists accepted the model at first because it explained the hydrogen emission spectrum.
However, with the development of quantum mechanics, scientists had to modify the model (not reject it).
Electrons still had specific energies, but they no longer travelled in fixed orbits.
Instead, electrons had a probability of being found in a given region of space.
Answer:
The intermolecular forces between water molecules are stronger than those between oxygen molecules. In general, the bigger the molecule, the stronger the intermolecular forces, so the higher the melting and boiling points.
