The half-life of a substance is 4 years. In how many years will 1/16 of the original amount remain?
A. 8 years
B. 20 years
C. 16 years
D. 12 years
Answer: Option C
Solution (By JKExamLibrary)
Fraction remaining = (1/2)^n = 1/16 => n = 4 half-lives. Time = n × half-life = 4 × 4 = 16 years. After 1 half-life: 1/2, 2: 1/4, 3: 1/8, 4: 1/16. Radioactive decay is exponential. So after 16 years, only 1/16th of original radioactive atoms remain.
Explanation:
Bakelite (phenol-formaldehyde) is thermosetting; once set, it cannot be remolded. Polyethylene, PVC, and nylon are thermoplastics – they soften on heating.
Explanation:
In a galvanic (voltaic) cell, chemical energy converts to electrical energy. Oxidation occurs at the anode, which is the negative electrode (electrons leave from it). Reduction occurs at the cathode, which is positive. This is opposite to electrolytic cell where anode is positive. Daniell cell: Zn anode (-), Cu cathode (+).
Explanation:
Smelting is the pyrometallurgical process of extracting a metal from its ore by heating it beyond its melting point and reducing the metal oxide with a carbonaceous reducing agent (like coke or coal). Flux is often added to remove impurities as slag. Calcination and roasting are oxidation processes.
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