(4) oxidation state is the correct answer.

Sodium, potassium, and cesium are located in the same column of the periodic table which means that they have the same oxidations state.  Atomic radius varies with both columns and rows and ionization energy varies with the atomic number.  The total number of protons also varies with the atomic number.

(4) copper is the correct answer.

Density tends to increase as you go down a column; You can compare the densities of these elements by examining Table S.

(4) Si, Ge, and As is the correct answer.

Metalloids are non-metals which exhibit some properties of metals.  They are located along the border of metals and non-metals on the periodic table.

In case you are not familiar with the metalloids, you can rule out any list which is known to contain non-metals, such as (2) which contains Carbon, (3) which contains oxygen.  In option 1, you likely will remember that aluminum is a metal, which leaves you with choice 4 as the only option.

(1) is the correct answer.

An isotope is an element with the same number of protons (atomic number) but a different number of neutrons.  You will need to remember that the top number refers to the number of neutrons and the lower number refers to the atomic number, or number of protons.  In this case, choice 1 is the only one that fulfills the definition for an isotope.

4) increasing first ionization energy is the correct answer.

Ionization energy increases from bottom to top and from left to right.  Atomic number also increases from left to right along the period so these trends correspond.

Group 1 metals react with water and easily lose electrons to form 1+ ions.

Another answer could be that they form ionic bonds with nonmetals.

Note: the question only asks for 1 chemical property.