A colloid is a mixture in which one substance of microscopically dispersed insoluble particles are suspended throughout another substance. However, some definitions specify that the particles must be dispersed in a liquid, and others extend the definition to include substances like aerosols and gels.

i. 

A n s w e r
Element mass % = mass ( g ) / At. mass %

Integral ratio of both =

P 27.3 12.

Q 72.7 16

2.275 /4.5= 1 / 2

Therefore, the Empirical formula is PQ2

According to the given reaction:

(i) 1 atom of A will react with molecules of B₂ = 1
300 atoms of A will react with molecules of B₂ = 300
But molecules of B₂ actually available = 200
∴  B₂ is the limiting reactant.

(ii) 1 mol of A reacts with 1 mol of B
∴ 2 mol of A will react with 2 mol of B.
Hence A is the limiting reactant.

A n s w e r

NaHCO3 + CH3COOH -----> CH3COONa + H2O + CO2 

Initial mass = 6.3 + 15 = 21.3 

Final mass = 18.0 + mass of CO2 

According to law of conservation of mass : 21.3 = 18.0 + mass of CO2 , 

Mass of CO2 = 3.3 g 

Avogadro Law

• It states that equal volumes of all gases under the same conditions of temperature and pressure
  contain equal number of molecules. Mathematically,

• The number of molecules in one mole of a gas = 6.022 ×10²³

According to the valence bond theory, Electrons in a molecule occupy atomic orbitals rather than molecular orbitals. The atomic orbitals overlap on the bond formation and the larger the overlap the stronger the bond.

The metal bonding is essentially covalent in origin and metallic structure involves resonance of electron-pair bonds between each atom and its neighbors.

• An atom consists of heavy positively charged nucleus. The whole mass of the atom is concentrated in the nucleus.
• The electrons in an atom revolve around the nucleus in definite circular paths called orbits or energy level.
• Each energy level is associated with definite amount of energy.
•  The change in energy takes place when electron jumps from one energy level to another energy level.

The reactant that is entirely used up in a reaction is called as limiting reagent.

3H₂ + N₂ → 2NH₃

In the reaction given above, 3 moles of Hydrogen gas are required to react with 1 mole of nitrogen gas to form 2 moles of ammonia. But what if, during the reaction, only 2 moles of hydrogen gas are available along with 1 mole of nitrogen.

In that case, the entire quantity of nitrogen cannot be used (because the entirety of nitrogen requires 3 moles of hydrogen gas to react). Hence, the hydrogen gas is limiting the reaction and is therefore called the limiting reagent for this reaction.

From weight percentage given
In PCl₃; 22.57 g of P combines with = 77.43 g of Cl and 1g of P would need = 3.43 g of Cl
and 
In PH₃; 91.18 g of P combines with = 8.82 g of H and 1g of P would need = 0.0967 g of H
​​​​​​their ratio is 35.47 

Now, if we consider the HCl; 
97.23 g of Cl need = 2.77 g of H 
Now, if we compare the ratio of Cl:H here = 97.23/2.77 = 35.10 

Now both the ratio are nearly equal (35.47:35.10) 
Hence, it follows the law of reciprocal proportions

Chemistry is the scientific discipline involved with elements and compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.

CO is isoelectronic with NO+ and N2.  CO has 14 electrons, 8 from oxygen and 6 from carbon. NO has 15 electrons 8 from oxygen and 7 from nitogen. But, as it becomes NO+, it loses an electron and the number of electrons is 14. Similarly, N2 has 14 electrons, 7 from each of the nitrogen atoms.

A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., without breaking chemical bonds.

This usually occurs in organic chemistry . Take acetic acid and formaldehyde and glucose.  

Acetic acid = CH3COOH - C2H4O2 Empirical formula = CH2O  

Formaldehyde = CH2O  

Glucose C6H12O6 = empirical formula = CH2O

Butene= molecular firmula is C4H8 but its empericsl formula is CH4

Preparation of Washing Soda

It is prepared by Solvay’s process.

(1) A cold and concentrated solution of sodium chloride is reacted with ammonia and carbon dioxide to obtain sodium hydrogen carbonate.

(2) Sodium hydrogen carbonate is separated by filtration,dried and heated.Oh heating sodium hydrogen carbonate decomposes to form sodium carbonate.

(3) Anhydrous sodium carbonate is dissolved in water and recrystallised to get washing soda crystals containing 10 molecules of water of crystallisation.

The Solvay process or ammonia-soda process is the major industrial process for the production of sodium carbonate. The ammonia-soda process was developed into its modern form by the Belgian chemist Ernest Solvay during the 1860s. The ingredients for this are readily available and inexpensive: salt brine and limestone.  The Solvay process is an industrial process that uses limestone (CaCO3 ) to produce carbon dioxide (CO2 ) which reacts with ammonia (NH3 ) dissolved in brine (concentrated NaCl(aq)) to produce sodium carbonate.

In first compound:
Weight percent of carbon = 42.9
Weight percent of oxygen = 100 - 42.9 = 57.1
In second compound:
Weight percent of carbon = 27.3
Weight percent of oxygen = 100 - 27.3 = 72.7
Now in first compound:
57.1 parts by weight of oxygen combine with 42.9 parts by weigh of carbon
 1 part by weight of oxygen will combine with

Now in second compound:
72.7 parts by weight of oxygen combine with 27.3 parts by weight of carbon
  1 part by weight of oxygen will combine with  parts of carbon.

The weights of carbon which combine with same weights of oxygen in two compounds bear a ratio 0·751 : 0·375 or 2 : 1. This is a simple ratio. Hence, the data illustrates the law of multiple proportion.
 

Atomic hydrogen or oxy-hydrogen torch involves the formation of atomic hydrogen atoms that are produced by dissociation of dihydrogen with the help of an electric arc.

In chemistry, a formal charge is the charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity.

 Given density of aqueous solution is 1.41 gm/ml of which 69% is nitric acid (HNO3).

So, 69% of 1.41 => 1.41 x 69/100 = 0.9729

Density of Nitric Acid = 0.9729 gm/ml

Now, Density = Mass/Volume. So,

0.9729 = Mass of HNO3/1000ml

Mass of HNO3 = 972.9 gm

No. of moles of HNO3 = Mass of HNO3/Molar mass of HNO3

                                       = 972.9/63                

                                       = 15.44 mol.

So Molarity of HNO3 = No. of moles of HNO3/Volume of Solution

                                    = 15.44/1 L

                                    = 15.44 M

(Note) : We find molarity because in the question it is asked to moles per litre which is molarity(M).

A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1Å. What is the uncertainty involved in the measurement of its velocity?

According to Heisenberg’s uncertainty principle.


Substituting the values in expression (1), we have