Iron, oxygen and water react with the iron creating a substance known to us as rust.
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Answer: The correct answer is black because the product of its side and mass is lower.
Explanation: Density of a substance is defined as the mount of matter that can be stored in a given volume.
Mathematically,

As, density is inversely proportional to the volume of the substance.
The substance will be more denser if it has less volume and it will be less denser if the volume is more.
We are given two cubes having different sides.
Volume of the cube is calculated by using the formula:

where, a = side of the cube.
Black: The side of this cube is 2 and volume will be =
Yellow: The side of this cube is 3 and volume will be =
As, the volume of black cube is less. So, this cube will be more denser.
Density of black cube: 
Density of Yellow Cube: 
Hence, black cube will be more denser because the product of its side and mass is lower.
The macronucleus is the larger elipse-shaped nucleus and takes care of
functions like respiration and digestion. In contrast to this, the
smaller micronucleus is only involved in cell division or reproduction.
Genetic applications in medicine can include studies of inheritance, mapping disease genes, diagnosis and treatment, and genetic counseling.
1) Chordata=A chordate is an animal of the phylum Chordata. All chordates possess 5 synapomorphies, or primary characteristics, at some point during their larval or adulthood stages that distinguish them from all other taxa
2) Vertebrates=vertebrate, also called Craniata, any animal of the subphylum Vertebrata, the predominant subphylum of the phylum Chordata. The vertebrates are also characterized by a muscular system consisting primarily of bilaterally paired masses and a central nervous system partly enclosed within the backbone.
3)Invertebrates=Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelid, and cnidarians.
4) Poikilothermic animals=A poikilotherm is an animal whose internal temperature varies considerably. Poikilotherms have to survive and adapt to environmental stress.
5) Homeothermic animals=The term homeothermic refers to the warm-blooded animals which have constant and relatively higher temperature. They are animals which can maintain their internal body temperature. Complete answer: Homeothermic animals are warm-blooded and maintain a constant body temperature, for example birds and mammals.
6) Oviparous= producing young by means of eggs which are hatched after they have been laid by the parent, as in birds.
7)Vivaparous=bringing forth live young which have developed inside the body of the parent
Sorry if it's incorrect
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