Which of these is a molecule?
a.
ca
c.
na
b.
mg
d.
h2o

The correct answer is option d.

Explanation:

Molecule is defined as group of two or more number of atoms. A molecule can be composed of same kind of atoms of same element or different kinds of atoms of different element.

For example: NaOH is the compound made up sodium atom, oxygen atom and hydrogen atom.

From the given option the is the molecules of water made up of 2 oxygen atoms and 1 hydrogen atom.

Where as other are symbol of the elements

how to make a simple air condition

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.