Answer:
The correct answer out of the four given options is
option a. light elements with atomic numbers less than 5
Explanation:
Big Bang nucleosynthesis, abbreviated as BBN, also known as primordial nucleosynthesis took place after the Big Bang for about 10 s to 20 minutes and resulted in the yield of isotopes of helium-4 (
), helium-3 (
) which accounts for most of the world's helium, other isotopes of hydrogen in small amounts like deuterium (D or
) and lithium isotope, lithium-7(
) in small amount.
Apart from these stable nuclei, it also yielded two radio-active isotopes: tritium(
) and beryllium-7(
) which due to their unstability later decayed into () and ().
All of these isotopes are of light elements with atomic number less than 5.
Answer:
Stream gradient refers to the slope of the stream's channel .It is the vertical drop of the stream over a horizontal distance.
Explanation:
Gradient is the slope or steepness of a stream channel. It affects the stream's velocity because the steeper the gradient is the greater the velocity due to gravity.
Drainage basin - the area of land drained by a river.
Catchment area - the area within the drainage basin.
Watershed - the edge of highland surrounding a drainage basin which marks the boundary between two drainage basins.
Source - the beginning or start of a river.
Confluence - the point at which two rivers or streams join.
Tributary - a stream or smaller river which joins a larger stream or river.
Mouth - the point where the river comes to the end, usually when entering a sea.
Hope this helped :)
