Answer:
Electromagnets are very widely used in electric and electromechanical devices, including:
Motors and generators.
Transformers.
Relays.
Electric bells and buzzers.
Loudspeakers and headphones.
Actuators such as valves.
Magnetic recording and data storage equipment: tape recorders, VCRs, hard disks.
The balanced equation of the combustion of the propane is

From the above chemical equation, it is clear that 1 mole of propane requires 5 moles of oxygen to undergo complete combustion as the result of this reaction, 3 moles of carbon-di-oxide and 4 moles of water molecules will be produced.
Therefore one-half mole of propane requires 2.5 moles of oxygen to undergo complete combustion. And in the reaction, 1.5 moles of carbon-di-oxide and 2 moles of water molecules are produced.
Therefore the answer is, 'One-half of propane combines with 2.5 moles of oxygen to produce 2 moles of water and 1.5 moles of carbon dioxide'
Correct answer choice is :
C) Force
Explanation:
In physics, a force is any cooperation that, when unrestricted, will vary the motion of an object. A force can create an object with mass to alter its velocity to accelerate. Force can also be defined intuitively as a push or a pull. A force acting on an object may create the object to alter shape, to start moving, to stop moving, to stimulate or decelerate. When two objects communicate with each other they exert a force on each other, the forces are just in size but different in direction.
The answer is B: it is a scalar measurement