<h2>Answers:</h2><h2 /><h2>a) Arrow B</h2><h2>b) Arrow E</h2>
Explanation:
Refraction is a phenomenon in which a wave (the light in this case) bends or changes its direction <u>when passing through a medium with a refractive index different from the other medium.</u> Where the Refractive index is a number that describes how fast light propagates through a medium or material.
According to this, if we observe the rays A an D passing throgh the biconcave lens, we will have two mediums:
1) The air
2)The material of the biconcave lens
This two mediums have different refractive indexes, hence the rays will change the direction.
-For the incident ray A, the corresponding refractive ray is B, because is the ray that bends after passing throgh the lens
-For the incident ray D, the refracted ray is E following the same principle.
Answer:
λ = 1360 m
Explanation:
Given data:
frequency of driving nails is given as 1 stroke per second mean at every 0.25 sec she hit the nails
speed of sound is given as 340 m/s
we know that the wave equation is given as
Speed = frequency × wavelength,
v = f × λ
where,
v = speed in meters/second (m/s)
f = frequency in Hertz (Hz)
substituing value to get wavelength of her driving nails


λ = 1360 m
Answer:
Gallium
Explanation:
Gallium is one such element used as a do/pant in a p-type semiconductor.
A do/pant is an impurity added to a semi-conductor used to alter its properties. Semi-conductors have a wide range of applications. They will conduct heat and electricity only under certain conditions. This property is highly desirable and find a wide application in electronics.
For p-type conductors, they are best do/ped with elements with 3 valence electrons. These are group 3 elements. From the choices, only gallium belongs to this group.
Other elements given are good do/pants for n-type semiconductors. They have 5 valence electrons.
Answer:
D
Explanation:
- The rate of the Diels-Alder is orders of magnitude faster if there is an electron-withdrawing group on the dienophile. For example, replacing a hydrogen on ethene with the electron-withdrawing group CN results in about a 10^5 increase in the reaction rate.
- Other common electron withdrawing functional groups that will accelerate the Diels Alder reaction of dienophiles include aldehydes, ketones, and esters.
- In short, any functional group conjugated with the pi bond which can act as a pi acceptor will accelerate a Diels-Alder reaction with a typical diene.
- See attachment for graphical explanation.