Answer:
Scandium
Explanation:
Mendeleev played an important role in the development of the modern periodic table. His periodic table was filled with gaps. He said that these gaps were elements that were yet to be discovered. He rightly predicted many elements which have now been discovered and fitted in their proper places in the periodic table.
He used the prefix ''eka'' to refer to elements whose properties were alike but were yet to be discovered at that time.
The compound named ekaboron which he predicted to have an atomic weight between 65 (zinc) and 75 (arsenic) with a valence similar to aluminum was later discovered in 1879 and properly named scandium.
Volcano experiment
Volcano lavatory
Volcano extravaganza
Volcano blow thrash
Average speed of the trip = 52 km/hr
<h3>Further explanation </h3>
Distance is the length traveled by an object within a certain of time .
Average speed = total distance/total amount of time ,
Can be formulated :

Total distance travelled : 1560 km
Total time : 8 hr + 12 hr + 10 hr = 30 hr

Answer:
Different types of hot or cold items can be stored in a thermos and power cannot enter or exit the system when the thermos lid is tightly closed
Explanation:
Closed systems are those that do not interact or do not exchange energy with the environment that surrounds them, that is why internal temperatures and conditions are maintained.
The human body is an open system, that is, it would be the opposite of the thermos since we constantly exchange energy with the environment through sweating, emission of gases, urine, feces, and the ingestion of food.
Thermoses are systems specially created to maintain a medium, it will be maintained if its lid is hermetically closed to prevent heat leakage or entry in situations of cold fluids.