Answer:
A.The hole in the ozone layer
Explanation:
• Montreal protocol is an international treaty that was signed to control the use of substances that are resulting in the depletion of the ozone hole.
This treaty was signed in the year 1987 and became effective form 1989.
• Since the time that this treaty has come into force, there has been a significant improvement in the ozone hole that was observed over Antarctic as it's size has decreased.
• This improvement has been possible because the treaty helped to phase out chemicals such as chlorofluorocarbons, carbon tetrachloride, etc. that are responsible for ozone hole depletion.
Hello! It is necessary for a scientist to do research prior to an experiment so they have more background on what they are going to examine. I hope this heps and feel free to rate my answer :)
Answer:
Explanation:
The primates have a hand feature which increases their fitness in the tree environment are the opposable thumbs. The thumbs are the broadest digit of the hand. The thumb can move in different directions in comparison to the other digits of the hand. This is an advantage in primates to hold and grasp the objects with their hands.
The monkeys climbing on the trees grasp the branches of trees to move from one tree to another.
The scientist who first organized the periodic elements according to its atomic weight was Alexander Emile Beguyer de Chancourtois. He was followed by John Newlands but they both had trouble arranging the properties because of some similarities that came out of the study.
It was Mendeleev who arranged the elements according to the atomic number that made the periodic table properly arranged he also knows that there are more elements that haven't been discovered.
Bone and blood cells are considered A. Specialized Cells
