Which ones do you need help on?
Answer:
All of the given statements are true.
Explanation:
All the elements are heavier than Bismuth (Bi) are radioactive.
The time for half of the original sample to spontaneous decay is called half life (
)

All radioactive elements are spontaneously decaying towards formation of a stable element.
Radioactive elements undergo decay in order to attain stability.
Radioactivity is a natural part of our environment. The earth also contains several primordial long-lived radioisotopes that have survived to the present in significant amounts.
Hence, all the given statements are true.
Each of the organic compounds mentioned has a general formula so that we can identify the classification of a certain substance. The compound CH₃CH₂OH is an alcohol because it follows the general formula R-OH, where R is a hydrocarbon chain. In this case, the hydrocarbon chain is ethane. When a hydroxyl functional group is attached, it becomes an alcohol whose name is ethanol.
The processes for the 3 types of weathering are,
biological: rocks worn down by plants
physical: water freezing and thawing in cracks of rocks
chemical: Acid rain
Hope this helped!!