JEE Chemistry - MCQ Practice Questions

Step 1: Identify the cathode and anode

In a galvanic cell, the electrode with the higher (more positive) standard reduction potential undergoes reduction at the cathode, and the electrode with the lower standard reduction potential undergoes oxidation at the anode.

Step 2: Apply the standard cell potential formula

Step 3: Substitute the values

In a galvanic cell, the anode is the electrode at which oxidation occurs, and the cathode is the electrode at which reduction occurs.

At the anode, a species loses electrons:

At the cathode, a species gains electrons:

A useful mnemonic is $\text{AN OX}$ and $\text{RED CAT}$: the anode undergoes oxidation, and the cathode undergoes reduction.

Therefore, the electrode reaction that occurs at the anode is:

Since $[{\text{H}}^{+}]=[{\text{OH}}^{-}]$, the solution is neutral.

Step 1: Verify the ion product of water.

At $25^{\circ }\text{C}$, the water dissociation constant is

Step 2: Calculate pH and pOH.

Step 3: Confirm neutrality.

Because $[{\text{H}}^{+}]=[{\text{OH}}^{-}]=1\times 10^{-7}\text{M}$, and $\text{pH}=\text{pOH}=7$, the solution is neither acidic nor basic.

Step 1: Identify the half-reactions

In the Zn–Cu galvanic cell, copper acts as the cathode (reduction) and zinc acts as the anode (oxidation):

Step 2: Apply the cell potential formula

Step 3: Substitute and calculate

Color of reactants has no effect on reaction rate. Temperature, catalyst, and concentration all significantly affect reaction rate.

H₂O has maximum boiling point due to strong hydrogen bonding compared to other hydrides in group 16

Cu²⁺ requires 2 electrons per atom. 1 Faraday = 1 mol of electrons; moles of Cu = $\frac{1}{2}$ = 0.5 mol

Diamond has a 3D tetrahedral covalent network structure with C-C bonds in all directions, while graphite has layered structure with weak van der Waals forces between layers

Kc depends only on temperature. Pressure, concentration changes, and catalysts do not alter Kc value—they shift equilibrium position but not the constant itself.

Cp - Cv = R = 8.314 J/(mol·K). Therefore, Cv = 29 - 8.314 ≈ 20.7 ≈ 20.8 J/(mol·K). This indicates a diatomic gas (Cp = $\frac{7}{2}$ R, Cv = $\frac{5}{2}$ R).

For first-order reaction, each half-life reduces concentration by 50%. After 1st half-life (10 min): 50% remains. After 2nd half-life (20 min): 25% remains = $\frac{1}{4}$th. Total time = 2 × 10 = 20 minutes.

2-bromobutane has a chiral center (C2 with four different groups: Br, H, CH3, and C2H5), exhibiting optical isomerism. Other options lack a true chiral center.

The structure has 5 carbons with main chain having OH at position 1 and two methyl groups at position 2. IUPAC name is 2,2-dimethyl-1-propanol.

Lucas reagent (HCl + ZnCl2) forms turbidity with primary alcohols immediately, secondary alcohols after 5 minutes, and tertiary alcohols instantly with dehydration.

In staggered conformation, bonds are maximally separated reducing electron-electron repulsion and torsional strain. Staggered is most stable with ~12 kJ/mol lower energy than eclipsed.

Friedel-Crafts alkylation using CH3Cl with AlCl3 as Lewis acid catalyst converts benzene to toluene. This is the standard industrial method for alkylbenzene synthesis.

The methyl group is electron-donating through inductive and hyperconjugative effects, making the benzene ring more electron-rich. This activates the ring for EAS and directs incoming electrophiles to ortho and para positions.

SN2 reactions proceed fastest with primary alkyl halides due to minimal steric hindrance around the carbon bearing the leaving group. CH3CH2Br (primary) > CH3CHBrCH3 (secondary) > (CH3)3CBr (tertiary).

PCC is a mild oxidizing agent that oxidizes primary alcohols to aldehydes without further oxidation to carboxylic acids (unlike acidic KMnO4 or K2Cr2O7).

Vicinal coupling (3J) between protons separated by 3 bonds typically has values of 6-18 Hz, with typical values around 7-8 Hz for anti-periplanar and 2-5 Hz for gauche conformations.