Answer:
3.83 m/s
Explanation:
Given that,
Distance covered by Jan, d = 4 miles
1 mile = 1609.34 m
4 miles = 6437.38 m
Time, t = 28 minutes = 1680 s
Jan's average speed,
v = d/t
Hence, the average velocity of Jan is 3.83 m/s.
The most important measure is awhips
Answer: C and D
Explanation: One of the first rule for total internal reflection to occur is that the ray must move from a dense to a less dense medium, hence refractive index of medium a must be greater than that of b.
When a ray moves from a dense to a less dense medium, the refracted ray moves away from the normal thus increasing the size of the angle of refraction (total internal refraction occurs when the angle of refraction is 90° and the angle of incidence at this point is known as the critical angle), hence the angle of incidence must be greater than the critical angle.
These points verifies option C and D
Answer:
Autotrophs
Explanation:
When you go down a food chain continuing to ask "what does it eat?" the last living thing that you will land upon is an autotroph.
Autotrophs are the primary producers as they (photoautotrophs) use the energy either from the sun to prepare there food by the process of photosynthesis or, more rarely, obtain chemical energy through oxidation (chemoautotrophs) to make organic substances from inorganic ones.
Autotrophs get consumed by the primary consumers in the food chain.
Answer:
(a) Most reactive 
Metal B
Metal D
Metal A
Least reactive Metal C
(b) (i) Bubbles should form very slowly
(ii) No reaction takes place
Explanation:
(a) The given metals arranged in their order of reactivity are;
Most reactive Metal B
Metal D
Metal A
Least reactive Metal C
The other of reactivity is based on the nature of their reactivity of the metals in air
(b) (i) Based on the reactivity of the metals in air, whereby metal A reacts very slowly and an oxide is formed, we have that, based on the reactivity of the metal A, when mixed with dilute hydrochloric acid, bubbles should form very slowly
(ii) Similarly, given that metal C is unreactive, we have that when small pieces of metal C are added to dilute hydrochloric acid, no reaction takes place.
