Daily Practice — today's mixed quiz

Question 1

Why is the Sun important for all life on Earth?

Accepted Answer

The Sun provides energy. Plants use sunlight to make food (photosynthesis). Without the Sun, plants could not grow, and without plants, no animal (including humans) could survive. The Sun is the ultimate source of all energy.

Question 2

Why did the cotton textile industry initially concentrate in Mumbai and Ahmedabad? How has this distribution changed?

Accepted Answer

COTTON TEXTILE — ORIGINAL CONCENTRATION IN MUMBAI AND AHMEDABAD: MUMBAI ('Cottonopolis'): (1) PORT: Mumbai's excellent natural harbour allowed easy import of raw cotton (including from Egypt for finer varieties) and export of finished textiles. (2) HUMID CLIMATE: Mumbai's high humidity (60–80%) prevented cotton yarn from breaking during spinning — a critical operational factor (cotton fibre is more elastic in humid conditions). (3) CAPITAL: Parsi and Gujarati merchant communities in Mumbai had capital accumulated from trade, which they invested in textile mills. India's first cotton textile mill opened in Bombay in 1854. (4) LABOUR: Large migrant labour pool from the Deccan provided mill workers. AHMEDABAD ('Manchester of India'): (1) Proximity to cotton-growing areas of Gujarat (Kheda, Surat, Bharuch districts). (2) Good rail connectivity to raw cotton regions. (3) Entrepreneurial community (Marwari, Bania) invested in mills. (4) Cheaper labour and land than Mumbai. CHANGES IN DISTRIBUTION: Since the 1980s, the cotton textile industry has DECENTRALISED: Old mill districts in Mumbai are being converted to commercial real estate (Lower Parel mill lands). Power-loom and decentralised production has spread to: Tamil Nadu (Coimbatore, Tiruppur), Maharashtra (Ichalkaranji, Solapur), Rajasthan (Bhilwara), Haryana (Panipat — 'City of Weavers'). Garment and readymade clothing: Tiruppur (hosiery), Bengaluru (garments), Delhi NCR (Noida garment export zone). Bangladesh, Vietnam, Cambodia have attracted more price-sensitive textile manufacturing as labour costs in India rose.

Question 3

A 9-year-old has had scanty foul-smelling right ear discharge for a year with an attic perforation. He now has headache, fever and neck stiffness. What has happened and what is required?

Accepted Answer

Cholesteatoma with an intracranial complication, most likely meningitis. Squamosal chronic otitis media is characterised by attic or marginal defects, scanty foul discharge and progressive bone erosion through osteoclast activation.

Erosion through the tegmen tympani gives access to the middle cranial fossa, producing meningitis, extradural abscess or brain abscess. He needs urgent cross-sectional imaging, joint ENT and neurosurgical involvement, intravenous antibiotics and surgical clearance of the disease. The principle to carry is that discharge volume is inversely related to danger: profuse mucoid discharge is mucosal and safe, scanty foul discharge is squamosal and destructive.

Question 4

Which molecule is paramagnetic?
(a) O₂ (b) N₂ (c) F₂ (d) H₂

Accepted Answer

(a) O₂.

O₂ has two unpaired electrons in its degenerate π* orbitals (by Hund's rule), making it paramagnetic. N₂, F₂ and H₂ have all electrons paired (diamagnetic).

Question 5

List and explain the specific atmospheric and oceanic conditions required for tropical cyclone formation.

Accepted Answer

Tropical cyclone formation requires a specific combination of conditions operating together, not any single factor alone. Sea surface temperature must reach approximately 27°C or higher, since this threshold provides sufficient heat and moisture energy to fuel the sustained deep convection a cyclone depends on. High humidity through the lower-to-middle troposphere is also required, since sufficiently moist air is necessary to sustain the cumulonimbus cloud development that forms a cyclone's core structure — insufficiently humid air would cause convective clouds to dissipate rather than build and organise. Low vertical wind shear — meaning wind speed and direction do not vary greatly with altitude — is similarly essential, since strong wind shear would disrupt a developing storm's vertical structure before it could organise and intensify. Finally, sufficient Coriolis force, generated by Earth's rotation, is required to initiate the storm's characteristic rotational structure, which is why formation is effectively impossible very close to the equator regardless of how favourable the other three conditions are. Together, these four conditions — adequate sea surface temperature, high humidity, low wind shear, and sufficient Coriolis force — must all be present simultaneously for tropical cyclogenesis to occur.

Question 6

Why should we protect plants and animals?

Accepted Answer

Because everything in nature is linked; protecting one helps the other and keeps the balance of nature.

Question 7

In reflection at a plane surface, the angle of incidence is 30°. The angle of reflection is:
(a) 30° (b) 60° (c) 15° (d) 90°

Accepted Answer

(a) 30°.

By the law of reflection, the angle of reflection equals the angle of incidence, both measured from the normal.

Question 8

Name the scientist who discovered the (a) electron, (b) proton, (c) neutron.

Accepted Answer

Step 1 — Recall the three discovery dates.
  Electron: J.J. Thomson, 1897 (cathode ray tube).
  Proton: E. Goldstein, 1886 (canal rays — anode rays). Later named by Rutherford.
  Neutron: James Chadwick, 1932.

✦ Answer: (a) J.J. Thomson, (b) E. Goldstein (with naming by Rutherford), (c) James Chadwick.

Question 9

If sin x = 1/3, find sin 3x.

Accepted Answer

sin3x = 3sinx − 4sin³x = 3(1/3) − 4(1/3)³ = 1 − 4/27 = 23/27. ✦ sin 3x = 23/27.

Question 10

The number of moles of an ideal gas occupying 22.4 L at 273 K and 1 atm is:
(a) 1 (b) 2 (c) 0.5 (d) 22.4

Accepted Answer

(a) 1.

At STP (273 K, 1 atm) one mole occupies 22.4 L, so n = 1. (Check: n = PV/RT = 1×22.4/(0.0821×273) ≈ 1.)

Today's daily practice

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