<span>A substance is composed entirely of one type of atom, it is known as a Chemical element
because mixture contain more than one type of atom and it cannot be neutron or isotope
so correct option is B
hope it helps</span>
Answer:
- Question 19: the three are molecular compounds.
Explanation:
<em>Question 19.</em>
All of them are the combination of two kinds of different atoms in fixed proportions.
- C₂H₄: two carbon atoms per four hydrogen atoms
- HF: one hydrogen atom per one fluorine atom
- H₂O₂: two hydrogen atoms per two oxygent atoms
Thus, they all meet the definition of compund: a pure substance formed by two or more different elements with a definite composition.
Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.
Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.
<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.
Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol
Water is H₂O. Its molar mass is 18.015g/mol
Calling x the number of water molecules in the hydrate, the percentage of water is:

From which we can solve for x:

Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:
Tearing paper, Physical Change
Weak bases are alkaline solution that does not get completely dissociated. The dissociation constant will be the ratio of the concentration of the products to the reactants.
<h3>What is a weak base ionization constant?</h3>
The weak base ionization constant is the equilibrium constant that is given as the division of the products of the ionization to the concentration of the reactants.
The reaction for HCO₃ is given as:
HCO₃⁻ + OH⁻ ⇄ CO₃²⁻ + H₂O
The value of Ka for the given reaction will be:
Ka = [CO₃²⁻][H₂O] ÷ [HCO₃⁻ ][OH⁻]
Therefore, the Ka of the weak carbonic acid is given as the ratio of the concentration of the products to the reactants.
Learn more about the weak ionization constant here:
brainly.com/question/27200344
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Answer:
14.7°C
Explanation:
Q = m·ΔT·c
ΔT = 
ΔT =
= 1320 J / ((230 g) * (.39 J/g°C)
ΔT = 14.7 °C