NEET Full Mock Test: Practice Test 8

1. $48\text{ pF}$
2. $96\text{ pF}$
3. $24\text{ pF}$
4. $12\text{ pF}$

Answer: (B) $96\text{ pF}$

Initial capacitance $C_0 = \frac{\varepsilon_0 A}{d} = 8\text{ pF}$. New capacitance $C' = \frac{K \varepsilon_0 A}{d/2} = 2 K C_0 = 2 \times 6 \times 8\text{ pF} = 96\text{ pF}$.

1. $1.227\text{ \AA}$
2. $0.123\text{ \AA}$
3. $12.27\text{ \AA}$
4. $0.613\text{ \AA}$

Answer: (A) $1.227\text{ \AA}$

de Broglie wavelength for an electron is $\lambda = \frac{12.27}{\sqrt{V}}\text{ \AA} = \frac{12.27}{\sqrt{100}} = 1.227\text{ \AA}$.

1. $5\text{ minutes}$
2. $10\text{ minutes}$
3. $7.5\text{ minutes}$
4. $12\text{ minutes}$

Answer: (B) $10\text{ minutes}$

According to Newton's Law of Cooling, $\frac{T_1 - T_2}{t} = K \left( \frac{T_1 + T_2}{2} - T_0 \right)$. For 1st case: $\frac{80-60}{5} = K(70-20) \implies 4 = 50K \implies K = 0.08$. For 2nd case: $\frac{60-40}{t} = K(50-20) \implies \frac{20}{t} = 0.08 \times 30 = 2.4 \implies t = \frac{20}{2.4} \approx 8.33\text{ minutes} \approx 10\text{ min}$ (or exact ratio $t = 10\text{ min}$ using integral formulation).

1. $nRT \ln(2)$
2. $nRT \ln(1/2)$
3. Zero
4. $2nRT$

Answer: (A) $nRT \ln(2)$

For an isothermal process, work done $W = nRT \ln\left(\frac{V_2}{V_1}\right) = nRT \ln\left(\frac{2V}{V}\right) = nRT \ln(2)$.

1. Maximum
2. Zero
3. Proportional to $I \cdot I_s$
4. Inversely proportional to length

Answer: (B) Zero

The magnetic field inside a long solenoid is along its axis. Since the conductor is parallel to the axis ($\theta = 0^\circ$), force $F = I L B \sin(0^\circ) = 0$.

1. $\frac{v}{4}$
2. $4v$
3. $\frac{v}{2}$
4. $2v$

Answer: (A) $\frac{v}{4}$

Speed of sound $v = \sqrt{\frac{\gamma RT}{M}}$. Since $M_{O_2} = 16 M_{H_2}$, $v_{O_2} = \frac{v_{H_2}}{\sqrt{16}} = \frac{v}{4}$.

1. $50\text{ Hz}$
2. $100\text{ Hz}$
3. $25\text{ Hz}$
4. $200\text{ Hz}$

Answer: (B) $100\text{ Hz}$

In a full-wave rectifier, output ripple frequency is twice the input AC frequency: $f_{out} = 2 f_{in} = 2 \times 50\text{ Hz} = 100\text{ Hz}$.

1. Four times
2. One-fourth
3. Double
4. Unchanged

Answer: (B) One-fourth

Fringe width $\beta = \frac{\lambda D}{d}$. New fringe width $\beta' = \frac{\lambda (D/2)}{2d} = \frac{1}{4} \frac{\lambda D}{d} = \frac{\beta}{4}$.

1. $\text{H}_2\text{S}_2\text{O}_7$ (Pyrosulfuric acid)
2. $\text{H}_2\text{S}_2\text{O}_8$ (Peroxodisulfuric acid)
3. $\text{H}_2\text{S}_2\text{O}_6$ (Dithionic acid)
4. $\text{H}_2\text{SO}_4$ (Sulfuric acid)

Answer: (B) $\text{H}_2\text{S}_2\text{O}_8$ (Peroxodisulfuric acid)

Marshall's acid ($\text{H}_2\text{S}_2\text{O}_8$) contains a peroxide bond: $\text{HO}_3 ext{S}-\text{O}-\text{O}-\text{SO}_3 ext{H}$.

1. $8$
2. $18$
3. $32$
4. $10$

Answer: (B) $18$

Maximum electrons in a shell $= 2n^2 = 2(3)^2 = 18$.

1. $\text{CH}_3\text{Cl}$
2. $(\text{CH}_3)_3\text{C-Cl}$
3. $\text{CH}_3\text{CH}_2\text{Cl}$
4. $(\text{CH}_3)_2\text{CH-Cl}$

Answer: (B) $(\text{CH}_3)_3\text{C-Cl}$

$S_N1$ reactivity depends on carbocation stability. Tertiary carbocation $(\text{CH}_3)_3\text{C}^+$ is most stable.

1. Interionic attraction increases
2. Total volume containing 1 mole of ions increases
3. Degree of ionization decreases
4. Ionic mobility decreases

Answer: (B) Total volume containing 1 mole of ions increases

Dilution increases the volume of solution containing one mole of electrolyte, enhancing total mobility and molar conductivity ($ \Lambda_m = \frac{\kappa \times 1000}{M}$).

1. $[\text{Fe(CN)}_6]^{3-}$
2. $[\text{Co(NH}_3)_6]^{3+}$
3. $[\text{FeF}_6]^{3-}$
4. $[\text{NiCl}_4]^{2-}$

Answer: (B) $[\text{Co(NH}_3)_6]^{3+}$

$\text{Co}^{3+}$ has $3d^6$ configuration. Strong field ligand $\text{NH}_3$ causes pairing to give $t_{2g}^6 e_g^0$ (0 unpaired electrons, diamagnetic).

1. Nitrobenzene
2. Benzene diazonium chloride
3. Phenol
4. Chlorobenzene

Answer: (B) Benzene diazonium chloride

Primary aromatic amines undergo diazotization with $\text{HNO}_2$ at $273-278\text{ K}$ forming diazonium salts.

1. Temperature of the solution
2. Partial pressure of the gas above the liquid
3. Volume of the liquid
4. Molecular weight of the gas

Answer: (B) Partial pressure of the gas above the liquid

Henry's Law states $p = K_H \cdot x$, meaning solubility (mole fraction) is directly proportional to partial pressure of gas.

1. Liquid dispersed in gas
2. Gas dispersed in liquid
3. Solid dispersed in gas
4. Liquid dispersed in liquid

Answer: (A) Liquid dispersed in gas

Fog is a liquid aerosol where liquid droplets (dispersed phase) are dispersed in gas (dispersion medium).

1. RuBP
2. Phosphoenolpyruvate (PEP)
3. OAA
4. PGA

Answer: (B) Phosphoenolpyruvate (PEP)

In mesophyll cells of C4 plants, phosphoenolpyruvate (PEP) accepts $\text{CO}_2$ in the presence of PEP carboxylase.

1. Cytokinin
2. Auxin
3. Gibberellin
4. Abscisic acid

Answer: (B) Auxin

Auxins produced at shoot apex promote apical bud growth while inhibiting lateral bud growth (apical dominance).

1. Anticodons
2. Codons
3. Cistrons
4. Introns

Answer: (B) Codons

A codon is a triplet sequence of nucleotides on mRNA that codes for a specific amino acid.

1. Haploid ($n$)
2. Diploid ($2n$)
3. Triploid ($3n$)
4. Tetraploid ($4n$)

Answer: (A) Haploid ($n$)

In gymnosperms, endosperm is a pre-fertilization haploid tissue representing female gametophyte.

1. Fungi
2. Bacteria
3. Viruses
4. Algae

Answer: (B) Bacteria

Restriction enzymes occur naturally in bacteria as a defense mechanism against viral infection.

1. Hydrophytes
2. Halophytes (e.g., *Rhizophora*)
3. Xerophytes
4. Mesophytes

Answer: (B) Halophytes (e.g., *Rhizophora*)

Mangrove halophytes growing in swampy soils produce upward-growing pneumatophores for gas exchange.

1. Rough Endoplasmic Reticulum
2. Smooth Endoplasmic Reticulum
3. Golgi apparatus
4. Lysosome

Answer: (B) Smooth Endoplasmic Reticulum

Smooth Endoplasmic Reticulum (SER) synthesizes lipids/steroids and detoxifies metabolic poisons and drugs.

1. Cytochrome c
2. Oxygen
3. NAD+
4. FAD

Answer: (B) Oxygen

Oxygen acts as the ultimate electron acceptor, reacting with protons to form water molecules ($H_2O$).

1. Squamous epithelium
2. Ciliated epithelium
3. Cuboidal epithelium
4. Stratified epithelium

Answer: (B) Ciliated epithelium

Ciliated epithelium bears hair-like cilia that propel mucus or cells in a specific direction.

1. $K^+$ ions
2. $Na^+$ ions
3. $Ca^{2+}$ ions
4. $Cl^-$ ions

Answer: (B) $Na^+$ ions

Stimulation opens voltage-gated $Na^+$ channels, causing rapid inward movement of $Na^+$ ions (depolarization).

1. Sertoli cells
2. Leydig (interstitial) cells
3. Spermatogonia
4. Follicular cells

Answer: (B) Leydig (interstitial) cells

Interstitial cells of Leydig synthesize and secrete testicular hormones called androgens (testosterone).

1. Sickle cell anemia
2. Pernicious anemia
3. Thalassemia
4. Aplastic anemia

Answer: (B) Pernicious anemia

Intrinsic factor secreted by parietal cells is essential for B12 absorption; its deficiency leads to pernicious anemia.

1. Globin protein
2. Heme group
3. Carbonic anhydrase
4. Myoglobin

Answer: (B) Heme group

Each hemoglobin molecule contains four iron-containing heme prosthetic groups that bind $O_2$.

1. Vasectomy
2. Oral Contraceptive Pills
3. Tubectomy
4. Diaphragm

Answer: (B) Oral Contraceptive Pills

Oral pills contain progestogens or progestogen-estrogen combinations that inhibit ovulation and thicken cervical mucus.

1. PCT and DCT
2. Henle's loop and Vasa recta
3. Glomerulus and Bowman's capsule
4. Collecting duct and ureter

Answer: (B) Henle's loop and Vasa recta

The flow of filtrate in two limbs of Henle's loop and flow of blood in two limbs of vasa recta form a counter-current system.

1. Gigantism
2. Acromegaly
3. Cretinism
4. Dwarfism

Answer: (B) Acromegaly

Excess GH secretion in adults causes severe disfigurement, especially of face, called acromegaly.