What is the difference between a quantity and a unit?
Answer:
Physical quantities are a characteristic or property of an object that can be measured or calculated from other measurements. Units are standards for expressing and comparing the measurement of physical quantities. All units can be expressed as combinations of four fundamental units.
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The given question is incomplete the options of the compete are:
A. On racecar tracks
B. In real-world conditions
C. In flooded environments
D. On closed courses
Answer: In real world conditions.
Explanation:
Fuel cell vehicles use hydrogen has as a fuel in order to run the car. Unlike the other conventional vehicle that run on fossil fuels and gasoline.
The hydrogen and oxygen combines together in order to power the the motor in the car. The electricity produced by the combination of this runs the car and the waste product is water.
They are also called as electronic cars but the main problem is that it has not been yet tested in the real world. There are many more physiological conditions that differ from place to place in the real world conditions.
Firstly, the cars needs to be tested in the real world and see where there are any advantages and disadvantages over conventional vehicles.
Hence, it is not available to the general public for purchase.
Answer:
2.11 * 10^3 molecules of phosphoric acid
Explanation:
<u>Answer:</u> The correct answer is Option A.
<u>Explanation:</u>
Standard enthalpy of formation is the change in enthalpy of one mole of a substance present at the standard state that is 1 atm of pressure and 298 K of temperature. The substance is formed from its pure elements under the same conditions.
We are given a chemical compound having chemical formula
This compound is formed by the combination of calcium, nitrogen and oxygen elements.
The chemical equation for the formation of from the components in their standard states follows:
Hence, the correct answer is Option A.
Answer:
b. First determine the mass of the sample and then convert it to the number of atoms using Avogadro's number and the molar mass of the element.
Explanation:
a. First determine the mass of the sample and then convert it to the number of atoms using the molar mass of the element. <em>FALSE. </em>As the mass is in grams and molar mass is in g/mol. This result in the moles of each element, not its number of atoms.
b. First determine the mass of the sample and then convert it to the number of atoms using Avogadro's number and the molar mass of the element. <em>TRUE. </em>Mass and molar mass will result in moles of element. These moles could be converted in number of atoms using Avogadro's number that is in # atoms per mole.
c.Use atomic microscope to determine Avogadro's number, then determine the mass of the sample and convert it to the number of atoms. <em>FALSE. </em>An atomic microscope is not used to determine Avogadro's number.
d.Use atomic microscope to count each atom. <em>FALSE. </em>There is not possible to count every single atom in an element. There are more atoms in a drop of water than stars in the sky.
I hope it helps!