Answer:
There are no options but the question can be answered based on general understanding of experimentation.
Group A: Control group
Group B: Experimental group
Explanation:
In an experiment, there are two groups viz: the control group and the experimental group. A control group is the group that does not receive any experimental treatment. It is considered the normal group while the experimental group is the group that is subjected to experimental treatment.
N.B: The experimental treatment in this case is the "Oxygen level"
According to the question, out of 20 petri-dishes used to grow bacteria, half (10) of the petri-dishes were placed in a container with normal atmosphere while the other 10 petri-dishes were placed in another container that have double the normal oxygen level. The first group of bacteria labelled GROUP A are the CONTROL GROUP because they were not given any treatment i.e placed under normal conditions while GROUP B are the EXPERIMENTAL GROUP because they are the group that received the experimental treatment (increased oxygen level).
For every, 3 Br- ions, 1 Al3+ ion reacts to form AlBr3.
Convert 16.2g of aluminum to moles:
16.2g Al / 27.0g per mol = 0.60 mols.
Based on the above ratio, 0.60 mols of Al will react with 1.8 mols of Br.
Convert 1.8 mols of Br to its mass:
1.8 mols Br × 79.9g per mol = 143.82g of Br.
Well when an object floats, a force pushes up on the object. The force then acts against the downward force of gravity. Which is called the buoyant force.( 8.8.c) The buoyant force on an object in a fluid is an upward force equal to the weight of the fluid the object has displaced.