Answer:
Explanation:
Physical changes changes when objects or substances undergo a change that does not change their chemical composition.
Answer:
The contributions are not listed in the question. I guess the following are the options you are talking about.
Same elements have same properties:
In 1803 Dalton gave the atomic theory that the properties of the atoms of the same element are same.
Electrons in Orbits:
Electrons were discovered in 1897 by J J. Thompson but the hypothesis of electrons in the orbits were given by Hantaro Nagaoka in 1904.
Plum pudding model:
Plum pudding model was given by J. J. Thompson in 1904 with the concept of positively charged medium containing the negatively charged electrons in it.
Positively Charged Atomic Nucleus:
Earnest Rutherford in 1911 discovered the positively charged atomic nucleus.
<u>Hydrogen bonds </u>are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.
- The hydrogen bond is weak bond.
- The hydrogen bond is electrostatic force of attraction between hydrogen atom and more electronegative atoms or group ( like Florine , oxygen or nitrogen) which is contently bonded.
- The hydrogen bond is occur in polar , contently bond atoms in different molecules.
- Example is H-O-H or

- The positively charged hydrogen side of one water molecule is bond with negatively charged oxygen side of another molecule.
learn about Hydrogen bond
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Answer:
7
Explanation:
7 mol AgCL * 
You can cancel out the "mol AgCl" to get 7 moles of AgNO3
Mole represents the a huge Avogadro number (way larger than atom), so we can eliminate option A and D.
And we know that Mercury is a solid , which mean it has greater mass than chlorine
So the answer is : B. 1.0 mol mercury (Hg) Atom