The pair of characteristics that you would use to place a fish in one of the three fish classes: agnatha, cartilaginous fishes, or bony fishes is by skeleton type and skin covering. The correct answer choice is:
Answer: A) skeleton type and skin covering.
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Answer:
yes
Explanation:
16
32
64
Answer:
B. 16 on E2020
Explanation:
B. Most of the nuclear radiation you are exposed to occurs naturally in the environment.
C. Naturally occurring nuclear radiation is called background radiation.
D. All natural radiation is at a level low enough to be safe.
Answer:
Option D
Explanation:
There are three major sources of background natural resources a) Terrestrial Radiation
; b) Internal Radiation and c) Cosmic Radiation
Cosmic Radiation is the radiation received from sun and stars. These radiations are received in traces as they go through different filters such as earth’s atmosphere, its elevation and magnetic field.
Terrestrial Radiations are received from radioactive minerals like uranium, radium and thorium. Since these minerals exists in soil and rock, their exposure is not harmful to mankind
Internal Radiation exists within the body of humans as radioactive potassium-40 and carbon-14 is presents with in the body since birth
Hence, option D is correct