The elements listed in the choices are radioactive materials. These materials are very unstable because of the high neutron-to-proton ratio in the nucleus. Because of this, they spontaneously undergo nuclear reactions by giving off sub-particles in order to lower the ratio. They emit radiation in the form of alpha, beta or gamma.
Half-life is the length of time it needs to completely react half of the original amount. For example, it would take Bismuth 60.5 seconds to use up half of its amount. Therefore, the lower the half-life the faster the reaction is and the lesser the residual amount will be. With that being said, the answer would be Bismuth because it only takes seconds.
Answer:
Caverns are created when moving groundwater mechanically weathers sediment and transports it elsewhere, leaving behind large empty spaces.
Explanation:
The movement of groundwater causes erosion that is responsible for the formation of caves. These caves are formed due to mechanical weathering of rocks. Mechanical weathering plays an major role in creating caverns by dissolving of limestone rock due to acidic water that reacts with limestone and removes it with the passage of time that forms caves. The normal pH water can't perform this job due to no reaction occurs with limestone.
We can not say that this areas are not civilized or to call them backwards. We may call them different. We can take for example the uses of animals in order to expand the commerce of their area. If we research about the use of camels, for example, we could see that it gained an special place within those who wanted to travel through many difficult areas like deserts. So in the case of camels they were not backwards, they used a different method to obtain success
Answer:
Explanation: Yes, he was always thinking.
