Which type of glass is used for making laboratory glassware and cookware due to its high thermal resistance?
A. Soda-lime glass
B. Quartz glass
C. Lead crystal glass
D. Borosilicate glass
Answer: Option D
Solution (By JKExamLibrary)
Borosilicate glass (e.g., Pyrex) contains boron trioxide (B₂O₃) along with silica, giving it low coefficient of thermal expansion, thus resistant to cracking under temperature changes. Soda-lime glass is ordinary glass, used for bottles, windows. Lead crystal has high refractive index for decorative items. Quartz glass (pure SiO₂) has very high melting point but is expensive. Borosilicate is ideal for beakers, test tubes.
Explanation:
In 1913, Niels Bohr modified Rutherford's model to explain atomic stability and emission spectra. He introduced the concept of quantized electron orbits (or energy levels), stating that electrons revolve in specific, fixed orbits without radiating energy, and they only emit or absorb energy when jumping between these discrete levels.
Explanation:
Faraday's First Law of Electrolysis states that the mass of a substance deposited or liberated at an electrode is directly proportional to the total charge (Q) passed through the electrolyte (m = ZQ, where Z is the electrochemical equivalent). The Second Law relates mass to equivalent weight.
Explanation:
Fermentation is an anaerobic biological process in which enzymes (zymase) convert glucose to ethanol and CO₂: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Oxidation would require oxygen. Esterification forms esters, saponification makes soap. Fermentation is used in brewing, winemaking, and baking (where CO₂ makes bread rise). The temperature is kept around 30-35°C.
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