The correct option is A an alkane
Let’s suppose a formula that can be alkane alkene or alkyne is CnH2n+X
Where n = Natural number
X =2 for alkane, 0 for alkene, and −2 for alkyne
Step 1: Mass of general formula CnH2n+x is
= n(C) + (2n+x )H
= n(12) + (2n+x )
= 12n +2n +x
= 14n + x
It is given that mass =7
Step 2: Equate mass of alkane with given mass
n(14) + X =72
Put the maximum value of n so that 14n should be less than 72 So, n=5
X= 72-14 × 5= 72-70
X=2
X is 2 for alkane