Question

1 Curie is
A) Activity of 1g of Uranium
B) 1 disintegration/second
C) $ 3.7 \times {10^{10}} $ Becquerel
D) $ 1.6 \times {10^{12}} $ disintegrations/second

Answer 1

Hint : Curie is a non-SI unit of radioactivity which is represented as Ci. It defines the number of decays per second of a radioactive compound called Radium.

Complete step by step answer
Curie is a unit of the radioactivity of a radioactive compound. Radioactivity is associated with unstable nuclei which can disintegrate into lighter nuclei through alpha beta or gamma radiation being emitted.
Curie is defined as the decays of radium atoms per second. It is also approximately equal to the amount of radioactivity emitted by 1 gram of radium−226.
1 Ci is equal to $ 3.7 \times {10^{10}} $ disintegrations per second, so 1 Ci also equals to 37 Becquerel (Bq). A curie is also a quantity of any radioactive compound that decays at a rate of 37 billion disintegrations per second (1 gram of radium-226, for example).
Hence option (C) is correct.

Additional Information
The curie is named for Marie and Pierre Curie, who discovered radium in 1898. The SI unit of radioactivity is Becquerel which is equal to 1 disintegration per second. The SI units gray and sievert are used for absorbed dose of radioactivity and dose equivalent for humans, which represent the risk of external radiation from sources outside the body. Ingesting even a millicurie of a radioactive compound is fatal to humans unless the radioactive isotope has a short halftime.

Note
To answer this question, we must be aware of the inter-conversions of different units of radioactivity. While Becquerel is the SI unit for measuring radioactivity, curie is still being used around the world for measurements of radioactivity in industries, labs, and hospitals.