Answer:
Elements having same valence electrons are placed in <u>same group.</u>
Explanation:
First, let's start with some basic concepts of modern periodic table:
1. Modern Periodic table : It is the arrangement of element in the increasing order of their atomic numbers
The Modern periodic table is divided into Periods and groups .
Periods : These are the horizontal rows. There are seven periods in the periodic table . Period 1 has 2 element. Period two and three has 8 elements , period 4 and 5 have 18 elements and the period 6 and 7 have 32 elements.
Same period have same number of atomic orbital(Shell)
Group : The group is the vertical columns . There are 18 groups in the modern periodic table.Those element which have same group number will also have same number of electron in their outermost shell. The number of electron in the outermost shell determines the valency of the element.
So, elements showing same valency are placed in same group.
All alkali are place in group 1 and have 1 valance electron in the outermost shell
Answer:- none
Explanations:- For naming hydrocarbons we use the suffix -ane, -ene and -yne.
-ane is used when we have only single bonds between all carbons. -ene is used if there is any double bond between two carbons and the -yne is used if there is any triple bond between two carbons.
The given name of the compound is propane. It ends at -ane and so it's an alkane and must have single bonds between all the carbons it has. So, there are zero double bonds present in 
.
This is also clear from the below lewis dot structure of the compound.
