When a mirror is rotated . . .
-- The incident ray doesn't turn. It's just the line from the source to the mirror.
It would be there, in the same place, even if there was no mirror.
-- The normal turns. It's the line perpendicular to the mirror, so it must turn
with the mirror.
-- Since the normal tuns and the incident ray doesn't, the angle between them
must change. And since the angle of the reflected ray is equal to the angle of
the incident ray, the reflected ray must also turn.
If a Substance conducts heat easily then it is considered a good conductor, since the electrons can move freely within the substance.
Answer:
Option B
Explanation:
The fundamental quantities are the basic quantities from which other quantities are derived.
There are a total of 7 fundamental quantities, namely Length, Mass, Time, Luminous Intensity, Amount of substance, Electric Current, Temperature.
From these 7 quantities, the other quantities are derived.
Weight is the product of its mass and the gravitational acceleration 'g' which acts on that mass.
Where mass is the fundamental quantity and 'g' is also derived and hence weight is a derived quantity.
For the first one, the correct answer would be "<span>Substance changes its form but not its molecular composition.". During a physical change (let's say cutting paper), the substance has its shape changed, but it is still itself (paper).
</span><span>The second one is a bit trickier: </span>
Kinetic energy of a molecule is directly influenced by temperature. If there is a higher temperature it will have a higher kinetic energy which means the molecule moves at a higher velocity. This will increase the chance of particles bouncing off of each other during the chemical reaction. That explains why the rate of reaction will be higher at a higher temperature, rather than higher at a cool temperature. The correct answer would be lower at 39F.
The given question is incomplete. The complete question is as follows.
Measurements show that the enthalpy of a mixture of gaseous reactants decreases by 338 kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that 187 kJ of work is done on the mixture during the reaction. Calculate the change in energy of the gas mixture during the reaction. Be sure your answer has the correct number of significant digits. Is the reaction exothermic or endothermic ?
Explanation:
The given data is as follows.
Change in enthalpy (
) = -338 kJ (as it is a decrease)
Work done = 187 kJ,
Change in energy (
) = ?
Now, according to the first law of thermodynamics the formula is as follows.
Hence, putting the given values into the above formula as follows.
Also, we know that W = 
so, 
= -151 kJ
Thus, we can conclude that the change in energy of the gas mixture during the reaction is -151 kJ.
