Answer ;
-An element is a substance containing only one type of atom, for example; H2 or 02 (consisting of atoms that all have the same number of protons).
-Microscopic, single atom of that element
-Macroscopic, sample of that element large enough to weigh on a balance
- A substance that cannot be broken down chemically; e.g; sodium metal,
Explanation;
-An element is a substance whose atoms all have the same number of protons: another way of saying this is that all of a particular element's atoms have the same atomic number. Elements are chemically the simplest substances and hence cannot be broken down using chemical reactions.
-An element is uniquely determined by the number of protons in the nuclei of its atoms.
Answer: acetone molecule ( CH₃-CO-CH₃)
Explanation:
1) Acetone is CH₃-CO-CH₃
2) That is a molecule (build up of covalent bonds).
3) When dissolved, covalent bonded compounds remain as separate molecules, then it is said that the major species present in the solution is the molecule. The molecules of acetone are surrounded (sovated) by the molecules of water.
This as opposed to the case of ionic compounds that ionize. When a compound as NaCl dissolves in water, it ionizes completely, so the major speceies are not NaCl formulas, but the ions Na⁺ and Cl⁻, not molecules.
That leads to the answer: the major species present when acetone is dissolved in water is the molecules of acetone (you do not need to state the fact that the molecules of water are part of the solution, because that is not the target of the question).
Answer: The actual yield of 
is 60.0 g
Explanation:-
The balanced chemical reaction :
Mass of 
=
According to stoichiometry:
1 mole of gives = 1 mole of
1.51 moles of gives =
moles of
Theoretical yield of 
Percent yield of = 
Thus the actual yield of is 60.0 g
The final temperature of the water is the equilibrium temperature, or the also the final temperature of the iron after a long period of time. Applying the conservation of energy:
m,iron*C,iron*ΔT = - m,water*C,water*ΔT
The density of water is 1000 g/mL.
(25 g)(0.449 J/g·°C)(T - 398 K) = - (25 mL)(1000 g/mL)(4.18 J/g·°C)(T - 298)
Solving for T,
<em>T = 298.01 K</em>
<span>The test dummy will continue forward until it makes contact with another object.</span>
