In an electrochemical cell, the salt bridge is used to:
A. Increase electrode potential
B. Prevent corrosion
C. Complete the circuit and maintain electrical neutrality
D. Increase current
Answer: Option C
Solution (By JKSSB Mock Tests)
The salt bridge (e.g., KCl-agar) allows migration of ions between half-cells, completing the circuit and maintaining charge neutrality. Without it, charge buildup would stop the reaction. It does not increase current or electrode potential. It prevents mixing of solutions. A porous membrane can also serve. Ions in the bridge must have similar mobility and not interfere with cell reactions.
Explanation:
Normal rainwater is slightly acidic (pH ~5.6) due to the dissolution of atmospheric CO2 forming carbonic acid. Acid rain is defined as precipitation with a pH lower than 5.6. It is caused by emissions of sulfur dioxide and nitrogen oxides, which react with water to form stronger sulfuric and nitric acids.
Explanation:
In the titration of a weak acid with a strong base, the equivalence point occurs in the basic region (pH > 7) due to the hydrolysis of the conjugate base formed. Phenolphthalein changes color in the pH range of 8.2 to 10.0, making it the most suitable indicator for detecting this basic equivalence point.
Explanation:
Niels Bohr in 1913 proposed the planetary model where electrons revolve in certain allowed circular orbits without radiating energy, with quantized angular momentum. Rutherford proposed the nuclear model but did not specify quantized orbits. Thomson gave plum pudding. Chadwick discovered neutron.
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