Question

(27) what were the criteria used by mendeleen an creating the periodic table.
(28) Gine seientific reason: On moving down ina graup, the atomie radiu afelementsofmireasegradually
(29) Why is it necessary to separateto separate oxygenated
and deoxygenated bload inmamals and brods.
(30) How do living thing get their food ?​

Answer 1

Answer:

27. Mendeleen used the atomic mass of elements to create the periodic table.

28. The atomic radius increases on moving downwards a group as new shells being introduced in an atom.

29. It is necessary to separate oxygenated and deoxygenated blood because it provides higher energy to each cell which helps in regulating constant body temperature.

30. Living things get their food from the surroundings. Plants makes food by photosynthesis. Animals gets it directly or indirectly from plants or by consuming other animals.