Answer:
D atom
Explanation:
The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms
One mole is always the same number: 6.02 * 10^ 23.
So, one mole of cars = 6.02 * 10 ^23 cars; one mole of pencils = 6.02 * 10^23 pencils; one mole of atoms = 6.02 * 10^23 atoms; one mole of molecules = 6.02 * 10^23 molecules.
So, all the options are correct: one mole of calcium ions has 6.02 * 10^23 representative particles, such as one mole of calcium nuclei and one of calcium atoms.
I think B. As an idea is just a way that could be possible
The electron geometry of a water molecule is tetrahedral even though the molecular geometry is bent.
As water molecule hybridisation is sp³ that provides it a electron geometry tetrahedral but due to presence of 2 lone pairs and 2 bond pairs its molecular geometry is bent.
The hybridisation sp³ makes electron geometry of a water molecule tetrahedral but the presence of 2 lone pairs makes its molecular geometry bent