Explanation:
Molar mass
The mass present in one mole of a specific species .
The molar mass of a compound , can easily be calculated as the sum of the all the individual atom multiplied by the number of total atoms .
(a) P₄
Molar mass of of the atoms are -
Phosphorous , P = 31 g/mol
Molecular mass of P₄ = ( 4 * 31 ) = 124 g/mol .
(b) H₂O
Molar mass of of the atoms are -
Hydrogen , H = 1 g/mol
oxygen , O = 16 g/mol.
Molecular mass of H₂O = ( 2 * 1 ) + ( 1 * 16 ) = 18 g/mol
(c) Ca(NO₃)₂
Molar mass of of the atoms are -
calcium , Ca = 40 g/mol
nitrogen, N = 14 g/mol
oxygen , O = 16 g/mol.
Molecular mass of Ca(NO₃)₂ = ( 1 * 40 ) + ( 2 * 14 ) + ( 6 * 16 ) = 164 g/mol.
(d)CH₃CO₂H (acetic acid)
Molar mass of of the atoms are -
Carbon , C = 12 g/mol.
oxygen , O = 16 g/mol.
Hydrogen , H = 1 g/mol
Molecular mass of CH₃CO₂H =( 2 * 12 ) + (2 * 16 ) + (4 * 1 ) = 60 g/mol.
(e) C₁₂H₂₂O₁₁ (sucrose, cane sugar).
Molar mass of of the atoms are -
Carbon , C = 12 g/mol.
oxygen , O = 16 g/mol.
Hydrogen , H = 1 g/mol
Molecular mass of C₁₂H₂₂O₁₁ = (12 * 12 ) + ( 22 * 1 ) + ( 11 * 16 ) = 342 g/mol.
Explanation:
the option you put in single displacement is a double displacement reaction and the first option you put in double displacement is actually a single displacement reaction
Answer: a. 
b. ![K_a=\frac{[HAsO_4^{2-}]\times [H_3O^+]}{[H_2AsO_4^{-}]}](https://tex.z-dn.net/?f=K_a%3D%5Cfrac%7B%5BHAsO_4%5E%7B2-%7D%5D%5Ctimes%20%5BH_3O%5E%2B%5D%7D%7B%5BH_2AsO_4%5E%7B-%7D%5D%7D)
Explanation:-
According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.
The balanced chemical equation is:
Here, 
is loosing a proton, thus it is considered as an acid and after losing a proton, it forms 
which is a conjugate base.
And, 
is gaining a proton, thus it is considered as a base and after gaining a proton, it forms 
which is a conjugate acid.
The dissociation constant is given by:
![K_a=\frac{[HAsO_4^{2-}]\times [H_3O^+]}{[H_2AsO_4^-]}](https://tex.z-dn.net/?f=K_a%3D%5Cfrac%7B%5BHAsO_4%5E%7B2-%7D%5D%5Ctimes%20%5BH_3O%5E%2B%5D%7D%7B%5BH_2AsO_4%5E-%5D%7D)
