<span>Changing atmospheric conditions, like increasing carbon dioxide content, might possibly increase the risk of global warming. Carbon dioxide, along with other greenhouse gases, is one of the leading causes of our Earth's rise in temperature. This is because greenhouse gases trap the planet's heat inside its atmosphere, preventing it from leaving the Earth's surface. </span>
<span>If the the level of water in a container is compared before and after the fusion, it can be realized that the ice has a higher level than that of liquid water: solid and liquid water does not have the same volume.
</span><span>We can generalize:
A state change always causes a change in volume.
Comment:
Water is an exception, volume increases during a melting for most of substances.</span>
Answer:
C) Ionic bonds
Explanation:
The ionic bonds are the strongest bond, it occurs when a metal donates electrons and a nonmetal gain these electrons. They'll be together by electrostatic force.
Metallic bonds it the second strongest bond, it occurs between metals, which loses electrons. It's an electrostatic force, but weaker than the ionic compound because it occurs between the cation and the electron.
Covalent bonds are the weakest bond. It happens between metals and nonmetals, or nonmetals and hydrogen or between atoms of hydrogen. The force that joins the atoms depends on the polarity of the molecule. Polar molecules have dipole forces, nonpolar molecules, induced dipole forces. Also, hydrogen makes special dipole forces with nitrogen, oxygen, and fluorine, called hydrogen bond.
As the stronger is the force, as difficult it will be to break it. So, ionic bonds will demand more energy to become gas, and have high melting points.
Answer: True.
Explanation.
The group 7A is actually named group 17.
That group is the halogens: F, Cl, Br, I, At, and Ts (Ts is one of the last elements discovered).
Those elements have 7 valence electrons (notice that it is the same number as the second digit in 17).
The atoms with 7 valence electrons will "easily" gain one electron to get the configuration of the next noble gas (8 valence electrons). That is why these elements gain electrons to form ions.
When atoms gain electrons form anions (negative ions). For example: F(-), Cl(-), Br(-), I(-).
