Which radioactive isotope is used in the treatment of cancer?
A. Iodine-131
B. Uranium-235
C. Cobalt-60
D. Carbon-14
Answer: Option C
Solution (By JKSSB Mock Tests)
Cobalt-60 is a gamma-ray emitter used in radiotherapy to destroy cancerous cells. Iodine-131 is used for thyroid cancer and disorders. Carbon-14 is used in radiocarbon dating. Uranium-235 is used as fuel in nuclear reactors and weapons. Radioisotopes for medical use are produced in nuclear reactors. Gamma rays penetrate and damage DNA of rapidly dividing cells.
Explanation:
Sea water is trapped in shallow pans and allowed to evaporate under sunlight, leaving behind crude salt. This is then purified. Distillation gives pure water, not salt.
Explanation:
Petroleum is a mixture of hydrocarbons with close boiling points. Fractional distillation uses a fractionating column to separate them efficiently based on repeated condensation–vaporization cycles. Simple distillation cannot separate liquids with boiling point difference less than 25 K effectively. Filtration and sublimation are not applicable.
Explanation:
Carbon-14 is a radioactive isotope of carbon with a half-life of about 5,730 years. It is continuously formed in the atmosphere and incorporated into living organisms. When the organism dies, C-14 decays. By measuring the remaining C-14, scientists can determine the age of archaeological and geological samples up to ~50,000 years old.
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