Answer:
Physical properties are used to observe and describe matter. Physical properties can be observed or measured without changing the composition of matter. These are properties such as mass, weight, volume, and density.
The two elements that have the same properties as sodium are potassium and rubidium .
<h3>What is periodic table?</h3>
The periodic table is an arrangement of the elements in order of increasing atomic number.
From the list, the two elements that have the same properties as sodium are potassium and rubidium .
Proton has an atomic number of 20 and a mass number of 40. The number of electrons is the same as the number of protons. Given that the atomic number is the number of protons present, we have 20 electrons and 20 protons.
Number of neutrons = Mass number - Number of protons
= 40 - 20 = 20 neutrons
Learn more about periodic table:brainly.com/question/11155928
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Answer:
Lavoisier made an important contribution to chemistry by the law of conservation of mass
Explanation:
The law of conservation of mass tell us, that the mass doens't change in a system. You have the same mass at the begining and in the end of a reaction.
Matter is neither created, nor destroyed in a chemical reaction.
This law also states that mass of reactants is the same of products in any chemical reaction
Answer:
1.95*10²² molecules are in 5.50 grams of AgNO₃
Explanation:
Being the molar mass of the elements:
- Ag: 107.87 g/mole
- N: 14 g/mole
- O: 16 g/mole
then the molar mass of the compound is:
AgNO₃: 107.87 g/mole + 14 g/mole + 3*16 g/mole= 169.87 g/mole
Then you can apply the following rule of three: if 169.87 grams of the compound are present in 1 mole, 5.50 grams will be present in how many moles?

moles= 0.0324
Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole. Avogadro's number applies to any substance.
You can apply the following rule of three: if by definition of Avogadro's Number 1 mole of the substance contains 6.023 * 10²³ molecules, 0.0324 moles how many molecules will it have?

molecules=1.95*10²²
<u><em>1.95*10²² molecules are in 5.50 grams of AgNO₃</em></u>