Answer:
Explanation:
The theory of natural selection was explored by 19th-century naturalist Charles Darwin. Natural selection explains how genetic traits of a species may change over time. This may lead to speciation, the formation of a distinct new species.
Answer is (4) - Se.
Among the given choices Se has the highest electronegativity value as 2.4 compared to others. Hence, Se shows <span>greatest attraction for electrons in a chemical bond.
</span>Electronegativity is
a value that tells us how an atom can attract electrons towards itself. <span>If
the electronegativity is high, then the attraction to the electrons is also high.
</span>
Answer:
John Dalton:
John Dalton was the scientist who introduced atomic theory in the field of chemistry. Dalton worked on different gases and formulated this theory. The main points of Dalton's theory are:
- Every element present is made up of atoms.
- Atoms of an elements are have the same same properties whereas these properties are different for each element.
- According to his theory, an atom could not be broken down.
- Different atoms combine or get separated from each other during a chemical reaction.
Ernest Rutherford:
Ernest Rutherford is known as the father of nuclear physics due to his impressing research work on radioactivity of atoms. Rutherford was the first scientist to discover the nucleus of an atom and prove that the nucleus was charged. He also described that the electrons circle around the nucleus of an atom.
Answer:
Magnesium nucleus will attract the electrons more toward it and therefore, shrinking the size of the atom. Magnesium atom is smaller than Calcium atom because Calcium has more electron ( 20e− ) which will occupy more energy levels ( n=4 for Calcium versus n=3 for Magnesium)
