The process of spontaneous emission of a, B and y rays from the nuclei of heavy elements is called
A Photoelectric effect
B Atomic spectra
C Radioactivity
D Fission reaction
Gamma rays rays are
A High energy electromagnetic radiations
B Positively charge particles
C Negatively charge particles
D Neutral particles
In which of the following pairs, the two substances forming the pair are chemically most dissimilar?
A Sugar and paper
B Butter and paraffin wax
C Chalk and marble
D Charcoal and diamond
The agent which is oxidized in photosynthesis is
A Sunlight
B Carbon dioxide
C Water
D Chlorophyll
The following are the half lives of four active isotopes. Which one of the following is the most dangerous to handle?
A 3 billion years
B 100 years
C 0.01 minute
D 13 days
The high reactivity of fluorine is due to
A Its high electro negativity
B Small size of fluorine atom
C Availability of d-orbitals
D Strong F - F bond
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