Related Questions

Disinfection of water is done to destroy pathogenic bacteria and thus prevent water-borne diseases. Disinfection of water may be done by the use of
A Ozone and iodine
B Chlorine or its compounds
C Ultraviolet light for irradiation of water
D All of the above
একটি ধাতব তলে λ তরঙ্গদৈর্ঘ্যের একবর্ণী আলোকরশ্মি আপতিত হলে ফটো-ইলেক্ট্রন নির্গত হয় এবং এক্ষেত্রে বিভবের মান 3Vo একই তলে যখন 2λতরঙ্গদৈর্ঘ্যের একবর্ণী আলো আপতিত হয়, তখন নিবৃত্তি বিভবের মান Vol ফটো-ইলেক্ট্রন নির্গত হওয়ার জন্য ঐ তলটির সূচন তরঙ্গদৈর্ঘ্যের মান নির্ণয় কর।(A monochromatic light of wavelength λ is incident on a metallic surface then ejects photo-electron and the value of stopping potential is 3Vo. When the same surface is illuminated by a light of wavelength 2λ., the stopping potential becomes Vo. Calculate the threshold wavelength for this surface to eject photo electrons.)
A 6λ
B 8λ
C 4λ3
D λ
E 4λ
The suitable method for disinfection of swimming pool water is
A Ultra violet rays treatment
B Lime treatment
C By using potassium permanganate
D Chlorination
The destruction of water-borne pathogens is termed as disinfection of water. Which of the following is a water disinfectant?
A Chlorine
B Alkalis
C Benzene hexachloride
D Alkyl benzene sulphonate (ABS)
The gas present in the stratosphere which filters out some of the sun's ultraviolet light and provides an effective shield against radiation damage to living things is
A helium
B ozone
C oxygen
D methane
The _____ is ultraviolet-light-erasable and electrically programmable. This allows the user to erase and store until programs and data are perfected.
A EPROM
B ROM
C PROM
D RAM
E None of the above
The memory which is ultraviolet light erasable and electrically programmable is
A ROM
B PROM
C RAM
D EPROM
E None of the above
Dose of chlorine for disinfection of water is about __________ mg/litre of water.
A 0.01
B 0.1
C 0.3
D 1
A common disinfectant used in village wells for disinfection of water is
A Free chlorine
B Bromine
C Iodine
D Potassium permanganate
Disinfection of water results in
A Removal of turbidity
B Removal of hardness
C Killing of disease bacteria
D Complete sterilisation

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