Answer:
The correct answer is C. element
Explanation:
The sample cannot be an element because an element - or <em>elemental substance</em> - cannot be decomposed into simpler substances. Thus, it cannot be composed by differents types of atoms. For example, an element is carbon (C).
As the sample contains <u>three types of atoms</u>, it can be a compound, a molecule or a mixture, because they can be composed by different types of atoms - of different chemical elements. For example, the sample could contain the element carbon (C) combined with other elements, for example oxygen (O) or hydrogen (H), amoing others.
The buoyancy of an object is dictated by its density. So let us calculate for density, where:density = mass / volume
Calculate the volume first of a solid cube:volume = (6 cm)^3 = 216 cm^3 = 216 mL
Therefore density is:density = 270 g / 216 mLdensity = 1.25 g / mL
Therefore this object will float in the layer in which the density is more than 1.25 g / mL.
Answer:
The answer is A. I took the test today.
Explanation:
Answer: C
Explanation:
In endothermic reactions, enthalpy is positive, and in exothermic reactions, enthalpy is negative, So, if enthalpy is positive, then it is an endothermic reaction, and hence is required for the reaction to occur.
Aqua regia is an oxidative mixture that is highly corrosive and is composed of hydrochloric acid and nitric acid. The Ea (rev) for the reaction is 3 kJ.
<h3>What is activation energy?</h3>
The activation energy is the minimum required energy by the reactant to undergo changes to form the product. The activation energy of the reverse reaction is given by the difference in the production state and transition state.
It is given as,
Ea (rev) = Ea (fwd) − ΔHrxn
Given,
ΔH° = 83KJ
Ea (fwd) = 86 kJ/mol
Substituting the values above as:
Ea (rev) = 86 - 83
= 3 kJ
Therefore, the activation energy of the reverse reaction is 3 kJ.
Learn more about activation energy, here:
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