Answer:
Option A = atomic masses
Explanation:
In compound molecular mass is the sum of the individual atomic masses of the atoms.
For example
Compound NaCl.
atomic weight of sodium = 23 g/mol
atomic weight of chlorine = 35.5 g/mol
Molar mass of NaCl = 23+ 35.5 = 58.5 g/mol
Every atom consist of nucleus or a positive center. The protons and neutrons are present with in the nucleus while electrons are present out side the nucleus. All these three subatomic particles construct an atom. The number of protons or number of electrons are the atomic number of an atom while the number of protons and number of neutrons are the mass number of an atom. A neutral atom have equal number of protons and electrons. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other.
Stored mechanical energy is energy stored and awaiting to be used and mechanical energy is the energy that was stored being used.
The empirical formula of this compound is 
<h3>Empirical formula </h3>
To calculate the empirical formula of a compound, the value of moles of each element is needed.
As we have the information of the mass value, we will use the molar mass expression, which corresponds to:
As the value of the empirical formula must be an integer, simply multiply the two values by a common factor:
So, the empirical formula of this compound is .
Learn more about empirical formula: brainly.com/question/1247523
Answer:
1.18×10²³ atoms.
Explanation:
From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ atoms.
From the above concept, 1 mole of sodium also contains 6.02×10²³ atoms.
1 mole of sodium = 23 g.
Thus,
23 g of sodium contains 6.02×10²³ atoms.
Therefore, 4.5 g of sodium will contain = (4.5 × 6.02×10²³)/23 = 1.18×10²³ atoms.
From the above calculation,
4.5 g of sodium contains 1.18×10²³ atoms.
The heat transfer just occurred is mainly conduction.
Conduction happens when two objects are in contact with each other. In the hotter object, the molecules and/or free electrons have a higher kinetic energy, thus they'll travel and collide into other molecules, resulting in spreading the energy to the other object.
The heat transfer happens until thermal equilibrium, where both objects have the same temperature and their molecules have the same kinetic energy rate.
In addition, radiation is also happening since everything that has a higher temperature than the environment is a net emitter. They release electromagnetic waves that turn out to be radiation. These occur even without the presence of air.
