Answer:
The elements become less reactive.
Explanation:
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction and reactivity increases because of greater electron affinity.
As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased. The electron affinity decreases because of shielding effect and thus atom become less reactive.
Atoms or molecule after gaining of electron possesses negative charge and is known as anion.
For the given sets:
The given elements are alkali metals and have tendency to lose electrons easily and form cations.
The given elements are non-metals and are electronegative. So, they gain electrons easily and form anion.
Carbon has tendency to form bond by sharing of electrons, Sulfur has tendency to gain electrons and form anion whereas Lead has tendency to lose electron.
Potassium and Iron has tendency to lose electron and form cation whereas Bromine has tendency to gain electron to form anion.
Hence, from the given sets, all elements of set: 
have tendency to form anions in binary ionic compounds.
<span>The number of neutrons bromine will have are equal to
= protons + neutrons
so,
80-35=45</span>
Answer:
condensing water
Explanation:
Entropy refers to the level of disorderliness in a system. The entropy of liquids is greater than that of solids. The entropy of gases is greater than that of liquids.
A process of physical change involving a change of state from solid to liquid or liquid to gas is accompanied by increase in entropy.
However, a change of state involving a change from liquid to solid or gas to liquid is accompanied by decrease in entropy.
Hence, steam condensing to water leads to decrease and not increase in entropy of the system.
Answer:
Examples of radioactive isotopes include carbon-14, tritium (hydrogen-3), chlorine-36, uranium-235, and uranium-238.
