H2o is an example of covalent molecule. H2O has two hydrogen atoms bonded to one oxygen atom. The two hydrogen atoms and the oxygen atom are linked together by a covalent bond.Atoms of oxygen are electronegative and attract the sharing of electrons in a covalent bond.
Answer:
4
Explanation:
Mass divided by Volume = Density
The objects mass is 200 grams and the volume of the water displaced is 50
So 200 divided by 50 equals 4
The pH of the solution : 12
<h3>Further explanation</h3>
Reaction
HCOOH + NaOH ⇒ HCOONa + H₂O
mol HCOOH =

mol NaOH =

Mol NaOH>mol HCOOH ⇒ at the end of the reaction there will be a strong base remains from mol NaOH, so that the pH is determined from [OH⁻]
ICE method :
HCOOH + NaOH ⇒ HCOONa + H₂O
4 5
4 4 4 4
0 1 1 1
Concentration of [OH⁻] from NaOH :

pOH=-log[OH⁻]
pOH=-log 10⁻²=2
pH+pOH=14
pH=14-2=12
Answer:
Density, 
Explanation:
Mass of a marble slab is 38.6 kg 38600 grams
The dimensions of the marble is 17 cm×23 cm×4 cm
We need to find its density. Mass per unit volume equals density. So,

So, the density of the marble slab is 
Answer:
Quantum mechanical atomic model.
Explanation:
The first model of electronic configuration was given by Bohr's model.
The most accurate model of electronic configuration is the quantum mechanical atomic model.
Bohr's model has various limitations:
1. It does not explain the Zeeman effect and stark effect.
2. It is not valid for multi-electron system.
3. Heisenberg uncertainty principle is not followed by this model
The quantum mechanical atomic model explains all the four quantum numbers for the electronic configuration of an atom in the periodic table.
The quantum mechanical atomic model considered the Heisenberg uncertainty principle.