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NEET Full Mock Test: Practice Test 2

Question paper with answer key. Selection Pro

Q1. A particle moves along a straight line such that its displacement at time $t$ is $x = 3t^2 - 12t + 5$. The velocity of the particle when its acceleration is zero is:
  1. $-12\text{ m/s}$
  2. $0\text{ m/s}$
  3. $6\text{ m/s}$
  4. $-6\text{ m/s}$

Answer: (A) $-12\text{ m/s}$

Velocity $v = \frac{dx}{dt} = 6t - 12$ and acceleration $a = \frac{dv}{dt} = 6\text{ m/s}^2$ (constant). Since acceleration is constant ($6\text{ m/s}^2$), velocity when $t=0$ or at any reference is calculated using expression $v(t)$. At $t=0$, $v = -12\text{ m/s}$.

Q2. An ideal gas undergoes an isothermal expansion from volume $V_1$ to $V_2$. The work done by the gas is:
  1. $nRT \ln\left(\frac{V_2}{V_1}\right)$
  2. $nRT \left(\frac{V_2}{V_1}\right)$
  3. $nRT \ln\left(\frac{V_1}{V_2}\right)$
  4. Zero

Answer: (A) $nRT \ln\left(\frac{V_2}{V_1}\right)$

For an isothermal process ($T = \text{constant}$), work done $W = \int P dV = nRT \ln\left(\frac{V_2}{V_1}\right)$.

Q3. Two electric dipoles of moment $p$ and $2p$ are placed in a uniform electric field $E$. The maximum torque experienced by the second dipole compared to the first is:
  1. Equal
  2. Double
  3. Half
  4. Four times

Answer: (B) Double

Maximum torque $\tau_{\max} = pE$. For dipole moment $2p$, $\tau_{\max} = 2pE$, which is double that of the first.

Q4. The self-inductance of a long solenoid is proportional to:
  1. Number of turns $N$
  2. Square of number of turns $N^2$
  3. $1/N$
  4. $1/N^2$

Answer: (B) Square of number of turns $N^2$

Self-inductance of solenoid $L = \frac{\mu_0 N^2 A}{l}$, so $L \propto N^2$.

Q5. In a Young's double slit experiment, if the distance between the slits is halved and the distance between slits and screen is doubled, the fringe width becomes:
  1. Unchanged
  2. Doubled
  3. Four times
  4. Halved

Answer: (C) Four times

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

Q6. A simple pendulum has time period $T_1$ on Earth's surface and $T_2$ at a height equal to radius of Earth $R$. The ratio $T_1/T_2$ is:
  1. $1:2$
  2. $2:1$
  3. $1:4$
  4. $1:\sqrt{2}$

Answer: (A) $1:2$

At height $h=R$, $g' = g/4$. Time period $T \propto 1/\sqrt{g}$. Thus $T_2 = 2 T_1$, so $T_1/T_2 = 1/2$.

Q7. The speed of sound in hydrogen gas at STP is $v$. The speed of sound in oxygen gas at STP will be:
  1. $4v$
  2. $v/4$
  3. $v/2$
  4. $2v$

Answer: (B) $v/4$

Speed of sound $v = \sqrt{\frac{\gamma RT}{M}}$. Molecular mass of $O_2$ is $16$ times that of $H_2$. Therefore, $v_{O_2} = \frac{v_{H_2}}{\sqrt{16}} = \frac{v}{4}$.

Q8. A p-n junction diode acts as a closed switch when it is:
  1. Forward biased
  2. Reverse biased
  3. Unbiased
  4. Lightly doped

Answer: (A) Forward biased

In forward bias, depletion layer width decreases and resistance becomes low, so it acts like a closed switch.

Q9. Which of the following molecules/ions is diamagnetic?
  1. $\text{O}_2$
  2. $\text{B}_2$
  3. $\text{N}_2$
  4. $\text{NO}$

Answer: (C) $\text{N}_2$

$\text{N}_2$ has $14$ electrons with all electrons paired in molecular orbitals, making it diamagnetic.

Q10. The solubility product ($K_{sp}$) of $\text{AgCl}$ is $1.0 \times 10^{-10}$. Its solubility in pure water is:
  1. $1.0 \times 10^{-5}\text{ M}$
  2. $1.0 \times 10^{-10}\text{ M}$
  3. $2.0 \times 10^{-5}\text{ M}$
  4. $1.0 \times 10^{-2.5}\text{ M}$

Answer: (A) $1.0 \times 10^{-5}\text{ M}$

For a 1:1 salt like $\text{AgCl}$, $K_{sp} = S^2 \implies S = \sqrt{K_{sp}} = \sqrt{10^{-10}} = 10^{-5}\text{ M}$.

Q11. In which of the following compounds does nitrogen exhibit the highest oxidation state?
  1. $\text{NH}_3$
  2. $\text{N}_2\text{H}_4$
  3. $\text{HNO}_3$
  4. $\text{NO}_2$

Answer: (C) $\text{HNO}_3$

In $\text{HNO}_3$, oxidation state of N is $+5$, which is its maximum oxidation state.

Q12. Which reagent is used to distinguish between ethane and ethyne?
  1. $\text{Br}_2/\text{CCl}_4$
  2. Ammoniacal $\text{AgNO}_3$ solution
  3. Bayer's reagent
  4. Cold dilute $\text{KMnO}_4$

Answer: (B) Ammoniacal $\text{AgNO}_3$ solution

Ethyne (terminal alkyne) contains acidic hydrogens and reacts with ammoniacal $\text{AgNO}_3$ (Tollens' reagent) to give a white precipitate, while ethane does not.

Q13. Equal volumes of two solutions of pH 3 and pH 5 are mixed. What is the pH of the resulting mixture?
  1. $4.0$
  2. $3.3$
  3. $3.5$
  4. $4.5$

Answer: (B) $3.3$

$[\text{H}^+]_1 = 10^{-3}$, $[\text{H}^+]_2 = 10^{-5}$. Total $[\text{H}^+] = \frac{10^{-3} + 10^{-5}}{2} \approx 5 \times 10^{-4}\text{ M}$. $\text{pH} = -\log(5 \times 10^{-4}) \approx 3.3$.

Q14. Glucose on reaction with concentrated $\text{HNO}_3$ gives:
  1. Gluconic acid
  2. Saccharic acid
  3. Sorbitol
  4. n-Hexane

Answer: (B) Saccharic acid

Strong oxidizing agent conc. $\text{HNO}_3$ oxidizes both the aldehyde group and primary alcohol group of glucose to dicarboxylic acid (Saccharic acid).

Q15. Which of the following transition metal ions is colored in aqueous solution?
  1. $\text{Sc}^{3+}$
  2. $\text{Ti}^{4+}$
  3. $\text{Cu}^+$
  4. $\text{Fe}^{2+}$

Answer: (D) $\text{Fe}^{2+}$

$\text{Fe}^{2+}$ has $3d^6$ configuration with unpaired d-electrons permitting d-d transition, making its solution colored. $\text{Sc}^{3+}$ ($3d^0$), $\text{Ti}^{4+}$ ($3d^0$), and $\text{Cu}^+$ ($3d^{10}$) are colorless.

Q16. Reimer-Tiemann reaction converts phenol into:
  1. Benzoic acid
  2. Salicylaldehyde
  3. Salicylic acid
  4. Benzaldehyde

Answer: (B) Salicylaldehyde

Phenol reacts with $\text{CHCl}_3$ and aqueous $\text{NaOH}$ (Reimer-Tiemann reaction) to yield Salicylaldehyde.

Q17. The site of perception of light in plants for photoperiodism is:
  1. Shoot apex
  2. Stem
  3. Leaves
  4. Roots

Answer: (C) Leaves

Leaves perceive the light stimulus for photoperiodism, which induces the synthesis of florigen (flowering signal).

Q18. Which cellular organelle is called the 'suicide bag' of the cell?
  1. Ribosome
  2. Lysosome
  3. Golgi apparatus
  4. Mitochondria

Answer: (B) Lysosome

Lysosomes contain hydrolytic enzymes and can digest damaged cellular components, earning them the name suicide bags.

Q19. In a food chain, maximum energy is present at the level of:
  1. Primary consumers
  2. Producers
  3. Secondary consumers
  4. Decomposers

Answer: (B) Producers

According to Lindeman's 10% law, producers capture and store maximum energy, which decreases at subsequent trophic levels.

Q20. The vascular bundles in dicot stem are characterized as:
  1. Conjoint, collateral, and open
  2. Conjoint, collateral, and closed
  3. Radial and open
  4. Concentric and closed

Answer: (A) Conjoint, collateral, and open

Dicot stem vascular bundles are conjoint, collateral, and open due to presence of cambium between xylem and phloem.

Q21. Which of the following is an example of an ex-situ conservation method for plants?
  1. National Parks
  2. Botanical Gardens
  3. Biosphere Reserves
  4. Sacred Groves

Answer: (B) Botanical Gardens

Botanical gardens and seed banks are ex-situ conservation approaches, whereas National Parks and Biosphere Reserves are in-situ.

Q22. During non-cyclic photophosphorylation, the primary electron donor to PS II is:
  1. $\text{NADPH}$
  2. Water ($\text{H}_2\text{O}$)
  3. Plastocyanin
  4. Ferredoxin

Answer: (B) Water ($\text{H}_2\text{O}$)

Photolysis of water provides replacement electrons to the reaction center $P_{680}$ of PS II.

Q23. The initiation codon in protein synthesis (translation) is:
  1. UAA
  2. UAG
  3. AUG
  4. UGA

Answer: (C) AUG

AUG codes for Methionine and serves as the universal start codon for protein translation.

Q24. Which plant hormone promotes stomatal closure under drought stress conditions?
  1. Cytokinin
  2. Abscisic Acid (ABA)
  3. Gibberellic Acid
  4. Auxin

Answer: (B) Abscisic Acid (ABA)

Abscisic acid (ABA) acts as a stress hormone and triggers rapid closure of stomata to prevent water loss.

Q25. Which part of the human brain regulates body temperature, hunger, and thirst?
  1. Cerebellum
  2. Hypothalamus
  3. Medulla oblongata
  4. Thalamus

Answer: (B) Hypothalamus

The hypothalamus contains thermoregulatory, satiety, and thirst centers in the brain.

Q26. Spermatogenesis is directly stimulated and regulated by which pituitary hormone?
  1. FSH
  2. LH / ICSH
  3. ACTH
  4. Prolactin

Answer: (A) FSH

FSH acts on Sertoli cells to stimulate factors needed for spermatogenesis.

Q27. Which type of epithelial tissue lines the inner surface of human fallopian tubes to move ova?
  1. Squamous epithelium
  2. Ciliated epithelium
  3. Cuboidal epithelium
  4. Columnar non-ciliated

Answer: (B) Ciliated epithelium

Ciliated columnar epithelium lines fallopian tubes and bronchioles to move particles/cells in a specific direction.

Q28. Which enzyme converts inactive fibrinogen into active fibrin during blood clotting?
  1. Thrombokinase
  2. Thrombin
  3. Prothrombin
  4. Renin

Answer: (B) Thrombin

Thrombin converts soluble fibrinogen into insoluble fibrin threads during blood coagulation.

Q29. T-lymphocytes mature in which primary lymphoid organ?
  1. Bone marrow
  2. Thymus
  3. Spleen
  4. Lymph nodes

Answer: (B) Thymus

T-lymphocytes originate in bone marrow but migrate to the Thymus for maturation.

Q30. The contraction of human heart muscle is initiated by impulse generated at:
  1. AV node
  2. SA node
  3. Purkinje fibers
  4. Bundle of His

Answer: (B) SA node

Sino-atrial node (SA node) acts as natural pacemaker of heart by generating action potentials spontaneously.

Q31. Which IUD releases progesterone hormone to prevent pregnancy?
  1. CuT
  2. Lippes loop
  3. Progestasert / LNG-20
  4. Multiload 375

Answer: (C) Progestasert / LNG-20

Progestasert and LNG-20 are hormone-releasing intrauterine devices (IUDs).

Q32. The volume of air inspired or expired during normal quiet breathing is called:
  1. Inspiratory Reserve Volume
  2. Tidal Volume
  3. Residual Volume
  4. Vital Capacity

Answer: (B) Tidal Volume

Tidal Volume (TV) is volume of air inspired or expired during normal respiration (~500 mL).