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NEET Full Mock Test: Practice Test 10

Question paper with answer key. Selection Pro

Q1. A uniform wire of resistance $R$ is cut into 5 equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is $R'$, then the ratio $R/R'$ is:
  1. 1/25
  2. 1/5
  3. 5
  4. 25

Answer: (D) 25

Each part has resistance $r = R/5$. In parallel, $1/R' = 5/r = 5/(R/5) = 25/R \implies R' = R/25$. Thus, $R/R' = 25$.

Q2. An ideal transformer has a primary to secondary turns ratio of $1:10$. If an alternating voltage of $220\text{ V}$ is applied across the primary, the secondary voltage will be:
  1. $22\text{ V}$
  2. $2200\text{ V}$
  3. $110\text{ V}$
  4. $440\text{ V}$

Answer: (B) $2200\text{ V}$

Transformer ratio $\frac{V_s}{V_p} = \frac{N_s}{N_p} \implies \frac{V_s}{220} = \frac{10}{1} \implies V_s = 2200\text{ V}$.

Q3. The angle of dip at the magnetic poles of the Earth is:
  1. $0^\circ$
  2. $45^\circ$
  3. $90^\circ$
  4. $180^\circ$

Answer: (C) $90^\circ$

At the magnetic poles, the magnetic field lines are perpendicular to the surface, so the angle of dip is $90^\circ$.

Q4. If the kinetic energy of a free particle is doubled, its de Broglie wavelength becomes:
  1. 2 times
  2. $\sqrt{2}$ times
  3. $1/\sqrt{2}$ times
  4. $1/2$ times

Answer: (C) $1/\sqrt{2}$ times

$\lambda = \frac{h}{\sqrt{2mK}}$. If $K' = 2K$, then $\lambda' = \frac{h}{\sqrt{2m(2K)}} = \frac{\lambda}{\sqrt{2}}$.

Q5. A satellite is revolving around the Earth in a circular orbit of radius $r$ with velocity $v_0$. The escape velocity from the same orbit is:
  1. $v_0$
  2. $\sqrt{2} v_0$
  3. $v_0 / \sqrt{2}$
  4. $2 v_0$

Answer: (B) $\sqrt{2} v_0$

Orbital velocity $v_0 = \sqrt{\frac{GM}{r}}$ and escape velocity $v_e = \sqrt{\frac{2GM}{r}} = \sqrt{2} v_0$.

Q6. A convex lens of focal length $20\text{ cm}$ is placed in contact with a concave lens of focal length $10\text{ cm}$. The power of the combination is:
  1. $+5\text{ D}$
  2. $-5\text{ D}$
  3. $+10\text{ D}$
  4. $-10\text{ D}$

Answer: (B) $-5\text{ D}$

$P_1 = \frac{100}{20} = +5\text{ D}$, $P_2 = -\frac{100}{10} = -10\text{ D}$. Net power $P = P_1 + P_2 = 5 - 10 = -5\text{ D}$.

Q7. The dimensions of stress are identical to those of:
  1. Force
  2. Pressure
  3. Energy
  4. Strain

Answer: (B) Pressure

Both stress and pressure are defined as Force per unit Area ($[M L^{-1} T^{-2}]$).

Q8. The half-life of a radioactive nucleus is $20\text{ minutes}$. What fraction of the original nucleus remains undecayed after $60\text{ minutes}$?
  1. 1/2
  2. 1/4
  3. 1/8
  4. 1/16

Answer: (C) 1/8

Number of half-lives $n = \frac{t}{T_{1/2}} = \frac{60}{20} = 3$. Remaining fraction $N/N_0 = (1/2)^3 = 1/8$.

Q9. Which of the following molecules has a non-zero dipole moment?
  1. $\text{CO}_2$
  2. $\text{BF}_3$
  3. $\text{NH}_3$
  4. $\text{CCl}_4$

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

$\text{NH}_3$ has a pyramidal geometry with a net dipole moment ($ \mu = 1.47\text{ D}$), whereas others are symmetrical with $\mu = 0$.

Q10. The oxidation state of Chromium in Potassium Dichromate ($\text{K}_2\text{Cr}_2\text{O}_7$) is:
  1. $+3$
  2. $+6$
  3. $+5$
  4. $+4$

Answer: (B) $+6$

$2(+1) + 2x + 7(-2) = 0 \implies 2x - 12 = 0 \implies x = +6$.

Q11. Which metal is purified by Mond process?
  1. Zinc
  2. Nickel
  3. Copper
  4. Zirconium

Answer: (B) Nickel

Mond process involves heating Nickel with carbon monoxide to form volatile nickel tetracarbonyl, which decomposes to give pure Nickel.

Q12. The conjugate base of $\text{HCO}_3^-$ is:
  1. $\text{H}_2\text{CO}_3$
  2. $\text{CO}_3^{2-}$
  3. $\text{CO}_2$
  4. $\text{OH}^-$

Answer: (B) $\text{CO}_3^{2-}$

A conjugate base is formed by removing a proton ($H^+$) from an acid. $\text{HCO}_3^- \rightarrow \text{H}^+ + \text{CO}_3^{2-}$.

Q13. Which carbohydrate is known as table sugar?
  1. Glucose
  2. Fructose
  3. Sucrose
  4. Maltose

Answer: (C) Sucrose

Sucrose, a disaccharide of $\alpha$-D-glucose and $\beta$-D-fructose, is commonly called table sugar.

Q14. For a first-order reaction, the half-life period ($t_{1/2}$) is related to rate constant ($k$) by:
  1. $t_{1/2} = \frac{0.693}{k}$
  2. $t_{1/2} = \frac{k}{0.693}$
  3. $t_{1/2} = \frac{[A]_0}{2k}$
  4. $t_{1/2} = \frac{1}{k [A]_0}$

Answer: (A) $t_{1/2} = \frac{0.693}{k}$

For a first-order reaction, $t_{1/2} = \frac{\ln 2}{k} = \frac{0.693}{k}$.

Q15. Which polymer is formed by condensation polymerization of ethylene glycol and terephthalic acid?
  1. Nylon 6,6
  2. Terylene (Dacron)
  3. Bakelite
  4. Teflon

Answer: (B) Terylene (Dacron)

Terylene (Dacron) is a polyester formed by condensation polymerization of ethylene glycol and terephthalic acid.

Q16. Reaction of Phenol with chloroform in presence of aqueous $\text{NaOH}$ followed by acidification yields:
  1. Benzoic acid
  2. Salicylaldehyde
  3. Salicylic acid
  4. Anisole

Answer: (B) Salicylaldehyde

This reaction is the Reimer-Tiemann reaction, which introduces an aldehyde group ($-CHO$) at ortho position relative to $-OH$ group of phenol.

Q17. The site of light reaction during photosynthesis in green plant cells is:
  1. Stroma of chloroplast
  2. Thylakoid / Grana
  3. Outer membrane of chloroplast
  4. Matrix of mitochondria

Answer: (B) Thylakoid / Grana

Light reactions (photochemical phase) occur in the thylakoid membranes / grana of chloroplasts.

Q18. During which phase of mitosis do chromosomes align at the equatorial plate?
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase

Answer: (B) Metaphase

At metaphase, all chromosomes move to the equator and align along the metaphase plate via spindle fibers.

Q19. Which nitrogen base is present in RNA but absent in DNA?
  1. Adenine
  2. Guanine
  3. Thymine
  4. Uracil

Answer: (D) Uracil

Uracil is present in RNA instead of Thymine which is found in DNA.

Q20. In a food chain, maximum energy is available at the level of:
  1. Primary consumers
  2. Producers
  3. Secondary consumers
  4. Decomposers

Answer: (B) Producers

Producers occupy the first trophic level and hold maximum energy according to Lindeman's 10% energy transfer rule.

Q21. Which plant hormone is responsible for ripening of fruits?
  1. Ethylene
  2. Gibberellic acid
  3. Auxin
  4. Abscisic acid

Answer: (A) Ethylene

Ethylene is a gaseous plant hormone that promotes fruit ripening and senescence.

Q22. Water potential of pure water at standard temperature and pressure is taken as:
  1. Zero
  2. 100
  3. 1
  4. Negative

Answer: (A) Zero

By convention, pure water at standard temperature and pressure has a water potential ($\Psi_w$) of zero.

Q23. The functional unit of inheritance made up of a specific sequence of DNA is a:
  1. Chromosome
  2. Gene
  3. Genome
  4. Plasmid

Answer: (B) Gene

A gene is the fundamental physical and functional unit of heredity.

Q24. Pollen grains are well-preserved as fossils due to the presence of:
  1. Pectocellulose
  2. Sporopollenin
  3. Lignin
  4. Suberin

Answer: (B) Sporopollenin

The exine layer of pollen grains is made of sporopollenin, one of the most resistant organic substances known.

Q25. The volume of air inspired or expired during a normal respiration in humans is called:
  1. Inspiratory Reserve Volume
  2. Tidal Volume
  3. Residual Volume
  4. Vital Capacity

Answer: (B) Tidal Volume

Tidal Volume (TV) is the volume of air inspired or expired during normal respiration (~$500\text{ mL}$).

Q26. Which blood group is known as the universal donor in humans?
  1. AB positive
  2. O negative
  3. O positive
  4. AB negative

Answer: (B) O negative

O negative blood lacks A, B, and Rh antigens, making it suitable for donation to any blood group.

Q27. Master endocrine gland that controls the function of other endocrine glands is:
  1. Thyroid gland
  2. Pituitary gland
  3. Adrenal gland
  4. Pancreas

Answer: (B) Pituitary gland

The pituitary gland secretes tropic hormones that regulate activities of other endocrine glands.

Q28. The structural and functional unit of human kidney is:
  1. Neuron
  2. Nephron
  3. Alveolus
  4. Hepatocyte

Answer: (B) Nephron

Nephron is the basic structural and functional unit responsible for urine formation in kidneys.

Q29. Which immune cell produces antibodies in response to pathogen invasion?
  1. T-lymphocytes
  2. B-lymphocytes
  3. Neutrophils
  4. Eosinophils

Answer: (B) B-lymphocytes

B-lymphocytes differentiate into plasma cells that synthesize antibodies.

Q30. Which muscle type is involuntary, non-striated, and uninucleate?
  1. Skeletal muscle
  2. Smooth muscle
  3. Cardiac muscle
  4. Voluntary muscle

Answer: (B) Smooth muscle

Smooth muscles are unstriated (smooth), involuntary, and contain single central nuclei.

Q31. In human female reproductive system, fertilization usually occurs in:
  1. Ovary
  2. Ampullary-isthmic junction of Fallopian tube
  3. Uterus
  4. Vagina

Answer: (B) Ampullary-isthmic junction of Fallopian tube

Fertilization occurs inside the fallopian tube, specifically at the ampullary-isthmic junction.

Q32. Which disease is caused by an extra copy of chromosome 21 (Trisomy 21)?
  1. Turner's syndrome
  2. Klinefelter's syndrome
  3. Down's syndrome
  4. Hemophilia

Answer: (C) Down's syndrome

Down's syndrome is a genetic disorder caused by autosomal trisomy of chromosome 21.