Answer:
a motor that requires no energy input once it is running
The observation, in this case, is quantitative.
<h3>Quantitative observation</h3>
Quantitative observations are observations that can be recorded based on quantitative data. In other words, they are observations that can be assigned numerical values.
Quantitative observations are as opposed to qualitative observations because the former cannot be assigned numerical values. They can be ranked or qualified.
In this case, Danielle and Heather could assign numbers to the length, width, and height of the tank in order to calculate its volume.
More on quantitative observations can be found here: brainly.com/question/17491501
Answer:
characteristic properties of an element are the defining properties of that element and it does not change with quantity of the element used.
Explanation:
the amount or the quantity of the element used does not affect the characteristic property of the element. it does not matter is the if the amount or the quantity of the element used in the reaction is large or the small the characteristic properties like boiling point, melting point, density, thermal conductivity, etc remain the same or remain constant.
Chemical reaction can be reversed if the energy of the reactants is less than the activation energy threshold.
<h3>
What is a reversible reaction?</h3>
A reversible reaction is a reaction in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously.
<h3>Conditions for reversible reaction</h3>
In equilibrium reaction, the activation energy of the forward reaction is more than that of backward reaction which causes bond breakage of the reactants.
Activation energy = (Threshold energy) - (Internal energy of the reactants)
Thus, a chemical reaction can be reversed if the energy of the reactants is less than the activation energy threshold.
Learn more about reversible reaction here: brainly.com/question/16614855
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