Atechnique that uses measurement of radioactive isotopes to evaluate the activity of the brain is

Magnetic resonance

Explanation:

Images of the brain in action can be obtained by functional magnetic resonance imaging, a method of injecting into the glucose vein labeled with radioactive isotopes, and analyzing through resonance its distribution to different brain areas, while performing functions such as walking, laughing, looking. for figures that arouse compassion, anger, sexual attraction, solidarity. According to this reasoning, magnetic resonance imaging is a technique that allows brain activity to be assessed by measuring radioactive isotopes.

answer: zinc is the substance which has a volume of 1.38 .

density is defined as the mass of an object per unit volume.

it can be calculated by dividing mass of a substance by its volume i.e.

si unit of density is kg per cubic meter and cgs unit of the same is gram per cubic centimeter.

now from the given data volume can be calculated by the formula .

hence, the volume of aluminium will be = which comes out to be 1.703 .

similarly, volume of zinc, chromium, and nickel will be 1.378 , 0.869 , and 0.356 respectively.