Ncert Solutions Chemistry Class 12th

Given: 
[Ag⁺] = 0.002 M
[Ni²⁺] = 0.160 M
n = 2
(n = moles of e- from balanced redox reaction)
E⁰cell= 1.05 V
Now, using the Nernst equation, we get,

Given: 
For hydrogen electrode, pH = 10
n = 1
(n = moles of e- from balanced redox reaction)
On using the formula [H+] = 10– pH

⇒ [H+] = 10 − 10 M
We know,

For a substance to oxidise Fe²⁺ to Fe³⁺ ion, it must have high reduction potential than Fe³⁺. The reduction potential of Fe³⁺ to Fe²⁺ reaction is 0.77V, the substances which have reduction potentials higher than this value will oxidise Fe²⁺ ions. Comparing the values, from the table:

NO, because Zn is very reactive with Cu. It reacts with copper sulphate to form zinc sulphate i.e., Zn displaces Cu and metallic Cu is also formed.
The reaction is given as:
Zn + CuSO₄ ⇒ ZnSO₄ + Cu

To determine the standard electrode potential of the system Mg²⁺|Mg, connect it to the standard hydrogen electrode (SHE). Keep the Mg²⁺|Mg system as cathode and SHE as cathode. This is represented as shown below.
Pt (s) | H₂ (g, 1 bar)| H⁺ (aq, 1 M) |Mg²⁺ (aq, 1M)| Mg
The electrode potential of a cell is given by
E^? = E^? R – E^? L
Where,  
E^? R- Potential of the half-cell in the right side of the above representation
E^? L- Potential of the half-cell in the left side of the above representation
It is to be noted that the potential of the standard hydrogen electrode is zero.
Therefore, E^? L = 0
E^?  = E^? R – 0 
⇒ E^? = E^? R

4.3 The order of the reaction is sum of the powers of concentration of reactants in the rate law. According to this,

The order of the reaction = 1/2 + 2

= 2 1/2 or 2.5

The order of the reaction is 2.5

4.2 Given-

Initial concentration (A₁) = 0.5M

Final concentration (A₂) = 0.4M

Time = 10 mins.

The formula for average rate of the reaction is,

r_av = -1/2 X Δ{A} / Δt → Equation 1

? {A} = (A₂)-( A₁), the equation 1 is written as,

r_av = -1/2 X A₂ - A₁ / Δt

= -1/2 X 0.4-0.5 / 10

= -1/2 X 0.1 / 10

= 0.005 mol L^-1 min^-1

= 5 * 10^-3 mol L^-1 min^-1

The average rate of the reaction is 5 * 10^-3 mol L^-1 min^-1

4.1 Given-

Initial concentration (R₁) = 0.03M

Final concentration (R₂) = 0.02M

Time = 25 mins.

The formula for average rate of the reaction is,

r_av = - Δ{R} / Δt → Equation 1

? {R} = (R₂)-( R₁), the equation 1 is written as,

r_av = - R₂ - R₁ / Δt

= -0.02-0.03 / 25

= 4 X 10^-4 mol L^-1 min^-1

The average rate of reaction in seconds is given by,

= 4 X 10^-4 mol L^-1 / 60 S

(dividing by 60 to convert minutes to seconds)

= 6.6 * 10^-6 mol L^-1 s^-1

The average rate of the reaction in minutes is 4 * 10^-4 mol L^-1 min^-1 and in seconds is 6.6 * 10^-6 mol L^-1 s^-1

14.1 

Glucose and sucrose are carbohydrates (optically active polyhydroxy aldehydes or ketones). 
Structure of glucose:

Structure of sucrose:

As you can see both the compounds have five –OH and eight –OH groups respectively. These –OH groups are responsible for the extensive hydrogen bonding with water. This –H bonding is responsible for the solubility of glucose and sucrose in water.

In case of cyclohexane or benzene (simple six-membered ring compounds), they do not contain any – OH groups. Hence, they cannot undergo –H bonding with water and are insoluble.