<span>Avogadro's number
represents the number of units in one mole of any substance. This has the value
of 6.022 x 10^23 units / mole. This number can be used to convert the number of
atoms or molecules into number of moles. We do as follows:
4.50 mol Fe ( 6.022x10^23 atoms / 1 mol Fe ) = 2.71x10^24 atoms Fe present </span>
Answer is A. Because K is potassium which is a metal
Answer : The correct option is, electrons are not shared equally between atoms.
Explanation :
Polar covalent bond : It is a type of chemical bond in which a pair of electrons are not shared equally between the two atoms.
In polar covalent bond, the electrons are not shared equally because one atom spends more time with the electrons than the another atom. In this, one atom has more tendency to pull an electron than the other atom.
For example : 
is an example of polar covalent bond. In water molecule, oxygen spends more time with the electron than the hydrogen and oxygen carries a partial negative charge.
Answer: A nuclear accident
Explanation:
The Chernobyl nuclear accident is level 7 (according to the International Nuclear Event Scale)<u>, due to the high impact that caused serious consequences on the environment and living beings.</u>
It should be noted that what happened in Chernobyl is considered one of the largest nuclear disasters in human history, because after the accident a large cloud with radioactive particles was found at a high altitude, scattering radiation all over the planet.
Furthermore, it is important to note that although the survival of wildlife in the Chernobyl region has currently been observed and some people still visit the site and others live there, the presence of humans in the place is prohibited.
