Question

1. Which of the following set of elements showed a reversal of atomic weights in Mendeleev's periodic table?

a. Zn and Cu
b. K and Pb
c. K and Ar
d. Co and Fe

2. Which element belongs to the Alkali metal Group

a. B
b. Be
c. Na
d. Al

3. The number of valence electrons determines

a. physical properties of an element
b. chemical properties of an element
c. both physical and chemical properties of n element
d. Neither physical nor chemical properties of an element

4. In the periodic table

a. there are two elements in the first period
b. there are 18 elements in the third period
c. the horizontal rows are called groups
d. the vertical columns are called periods​

Answer 1

Answer:

1. Zn and Cu

2. Na

3. The number of valence electrons in an atom governs its bonding behavior. Therefore, elements whose atoms can have the same number of valence electrons are grouped together in the periodic table of the elements.

4. The vertical columns known as group.