The ch4 molecule exhibits hydrogen bonding.
This statement is false. A CH4 molecule do not have a hydrogen bonding instead it has dipole dipole attraction.
Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O, or F atom.
This would be a true statement. A hydrogen bond is present when an atom of hydrogen shares electrons with O, N or F atom.
A hydrogen bond is equivalent to a covalent bond.
This is a false statement. A hydrogen bond is an intermolecular force of attraction while covalent bond is a intramolecular force. So, they would mean different things.
a hydrogen bond is possible with only certain hydrogen-containing compounds.
This would be true. Without the presence of an hydrogen atom definitely there would be no hydrogen bond.
a hydrogen atom acquires a partial positive charge when it is covalently bonded to an f atom.
This would be true since a HF is a polar molecule.
Explanation:
It is given that,
The time period of artificial satellite in a circular orbit of radius R is T. The relation between the time period and the radius is given by :

The radius of the orbit in which time period is 8T is R'. So, the relation is given by :



So, the radius of the orbit in which time period is 8T is 4R. Hence, this is the required solution.
The metric system is based on powers of 10 so it is much easier to convert units, often just by moving the decimal point.