A sample of galena is contaminated with zinc blende.Name one chemical which can be used to concentrate galena selectively by froth floatation
method.
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Food cans are coated with tin and not with zinc because (a) zinc is costlier than tin.
(c) Food cans are coated with tin and not with zinc because zinc is more reactive than tin.
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A sample of AlF3 contains 3*10^24 F- ions. The number of formula units of this sample is :(Options in description)
Here, AlF3 is an ionic compound in which one formula unit of this has three fluoride ions attached to it. So, in 3 x 1024 number of fluoride ions, number of formula units...
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The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes 8 X 16 and 8 X 18 in the sample?
Since average atomic mass = 16 x X + 18 x (100 – X )/100 16.2 = 16X + 1800 – 18X/100 1620 = – 2X + 1800 2X = 1800 – 1620 X =...
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(a) The average atomic mass of a sample of an element X is 35.5u. What are the percentages of isotopes 17X37 and 17X35 in the sample ?
(a) Let the percentage of 17X 37 is p Percentage of 17X 35 = (100 – p) Average atomic weight = 35.5 Therefore 35.5 = 37p + 35(100 − p) /100 3550 = 37p + 3500 − 35p 3550...
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A sample of vitamic C is known to contain 2.58 ×1024 oxygen atoms. How many moles of oxygen atoms are present in the sample?
1 mole of oxygen atoms = 6.023×1023 atoms ∴Number of moles of oxygen atoms = 2.58 ×1024 / 6.022×1023 ...
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A gold sample contains 90% of gold and the rest copper. How many atoms of gold are present in one gram of this sample of gold?
One gram of gold sample will contain 90/100 =0.9g of gold Number of moles of gold = Mass of gold/ Atomicmass of gold ...
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You are given two samples of water labelled as ‘A’ and ‘B’. Sample ‘A’ boils at 100°C and sample ‘B’ boils at 102°C.
Sample ‘B’ will not freeze at 0°C because it is not pure water. At 1 atm, the boiling point of pure water is 100°C and the freezing point of pure...
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Out of zinc and tin, which one protects iron better even after cracks and why ?
Zinc protects better because oxidation of zinc is greater but that of tin is less than that of iron.
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In a lake contaminated with pesticides, which one of the following organism living in the lake will contain the maximum amount of pesticide?
The concentration of pesticide will increase with the rise of trophic level in the food chain. Phytoplankton -----> Zooplankton ---> Small fish -----> Big fish (maximum pesticide) Therefore, big fishes will have maximum...
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When the sample of copper wth zinc impurity is to be purified by electrolysis,
(d) : The impure metal is made anode while a thin sheet of pure metal acts as cathode. On passing the current, the pure metal is deposited on the cathode...
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