A sedimentary rock can become an igneous rock by melting and solidification.
One fourth means (one half) of (one half) .
So the 18 months must be two half-lifes.
The half-life of this particular isotope is 9 months.
Vertebrates have a bilateral symmetry due to which their entire body is divided into right and left halves while the invertebrates either have radial symmetry or the bilateral symmetry. Therefore, option D is correct.
The other basic differences between the vertebrates and the invertebrates are that vertebrates have a spinal cord and a backbone while invertebrates lack them, vertebrates have well developed brain, lungs or gills in respiratory system and closed circulatory system.
Answer:
Organism.
Explanation:
The cell is the smallest form of life. Cells work together to form tissues, tissues work together to form organs, and organs work together to create an organ system, and organ systems work together to create organisms. I believe "organism" includes all of these other levels.
When air is heated up the molecules spread out and move faster, so heat rises because it is less dense than the cooler air around it.
