Answer : The structure are shown below and the number of stereoisomers are possible in 3,5-dimethylnonane and 3,7-dimethyle-5-ethyldecane are 4 and 8 respectively.
Explanation :
Chiral carbon : It is carbon which is attached to the different types of atoms or molecules.
The number of stereoisomers possible for a compound is related to the number of chiral centers (n) present in it as,

where,
'n' is the number of chiral carbon present in the compound.
The number of chiral carbon present in 3,5-dimethylnonane is, 2 that means n = 2 (carbon-3 and carbon-5)

The number of stereoisomers are possible in 3,5-dimethylnonane is, 4
The number of chiral carbon present in 3,7-dimethyle-5-ethyldecane is, 3 that means n = 3 (carbon-3, carbon-5 and carbon-7)

The number of stereoisomers are possible in 3,7-dimethyle-5-ethyldecane is, 8
The answer Should be C) CF4
Fam
Answer: Option (a) is the correct answer.
Explanation:
Force of gravity is defined as the force which can attract any object along with its mass.
For example, an apple falling from a tree on the ground represents that force of gravity has pulled the apple towards the ground along with its mass.
Thus, we can conclude that out of the given options, it is a force of attraction is true about the force of gravity.
Answer:
neck
Explanation:
through the neck and opening of the thermos, where there is no vacuum.. hence heat is easily transmitted resulting into heat loss