Question

1.Oxygen (O) is a gas found in the 16th column of the periodic table. What statement is true about oxygen and the other elements in that column?
A.All the elements in the column have similar chemical properties.


B.All the elements in the column are in the same period.


C.All the elements in the column are nonreactive.


D.All the elements in the column have the same number of protons



2.Why are all of the substances on the periodic table classified as elements?



All elements are pure substances.


Substances on the periodic table cannot be dissolved in water or other liquids.


Substances on the periodic table can be combined to form compounds and are therefore elements.


Substances on the periodic table cannot be broken down into other substances and are therefore elements.

Answer 1

Answer:

For 1: The correct answer is Option A.

For 2: The correct answer is substances on the periodic table cannot be broken down into other substances and are therefore elements.

Explanation:

• For 1:

Oxygen is the 16th element of the periodic table. Atomic number of an element determines the number of protons present in that element. So, the number of protons in oxygen atom is 16.

Elements in a periodic table are distributed in 7 Periods and 18 Groups.

Periods are the horizontal lines (rows) in a periodic table.

Groups are the vertical lines (columns) in a periodic table.

Elements that belong to same group show similar chemical properties because they have same number of valence electrons.

Hence, the correct answer is Option A.

• For 2:

Elements are defined as the chemical species that have similar kind of atoms. All the atoms in an element have same atomic number.

Elements cannot be broken down into other substances.

For Example: Sodium, oxygen etc..

Hence, the correct answer is substances on the periodic table cannot be broken down into other substances and are therefore elements.

Answer 2

1. A. All the elements in the column have similar chemical properties.

2. Substances on the periodic table cannot be broken down into other substances and are therefore elements.