Your mass can never change no matter where you are since mass is the amount of matter you contain. By going to the moon, you do become lighter due to the weaker gravity but the amount of matter that you are made of (your mass) does not change.
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Answer:
Cl2
Explanation:
Cl2 is a covalent molecule because it contains 2 non-metal elements.
It is non-polar because both elements have the same level of electrostatic attraction (remember that electrostatic attraction is the tendency to steel an electron from an element with lower a lower electrostatic force)
In Cl2 since there are only 2 molecules that are the exact same there is no overall dipole (which means that one end of the molecule is slightly positive or negative charge)
If the molecule replaced one Cl or something else then it would be non-polar since one element will be more electrostatic than the other and one region of the molecule will have a slightly positive or negative charge, unless the molecule is symmetrical like CH4.
For CH4 (methane) if you drew this as a lewis structure the Carbon would be surrounded by 4 hydrogen atoms meaning the overall dipole will be cancelled out since the molecule is symmetrical.
You may not understand the last part but just know that:
If there are 2 of the same atoms in the molecule (Cl2) then it is non-polar
If there are 2 non-metals then the bond is covalent
Water is always polar
A chemical bond that involves the transfer of electrons from a metal to a nonmetal and thus forms ions and the atoms in the molecule are attracted towards each other through electrostatic force of attraction are said be ionic bond. In short, the bond formed between the two oppositely charged ions.
In salt, the compound formed between sodium and chlorine is sodium chloride having molecular formula where sodium is a metal and chlorine is the non-metal. The formation of the compound takes place by transfer of an electron from sodium thus forming a cation of formula to chlorine which gains electron and thus results in an anion formation having formula . The force of attraction between these oppositely charged ions that helds them together and results in formation of compound is electrostatic force of attraction.
Hence in salt, the nature of bond between sodium and chlorine is ionic.
Pressure - Force per unit area
Hope it helped :)