The most important ore of aluminium is
Answer: A
Bauxite, hydrated aluminium oxide \(\mathrm{Al_2O_3\cdot 2H_2O}\), is the most important ore of aluminium.
It is purified to alumina by the Bayer process and then reduced electrolytically in the Hall–Héroult cell. Haematite and magnetite are iron ores and monazite a thorium ore.
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The law which states that the amount of gas dissolved in a liquid is proportional to its partial pressure is
Answer: C
This is Henry's law.
\[p = K_H\, x\] where \(x\) is the mole fraction of the dissolved gas and \(p\) its partial pressure above the liquid. It explains why a fizzy drink releases gas when opened, and why divers ascending too quickly suffer decompression sickness as dissolved nitrogen comes out of the blood.
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The gas used for artificial ripening of green fruit is ?
Answer: B
Ethylene ripens green fruit artificially.
It is the plant's own ripening hormone, and a few parts per million in a closed chamber will start the breakdown of chlorophyll and the conversion of starch to sugar. Because it is a gas, one ripening fruit hastens the ripening of others beside it.
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The number of neutrons in dipositive Zinc ion is
Answer: D
The \(\mathrm{Zn^{2+}}\) ion contains 35 neutrons.
Zinc has \(Z=30\) and a mass number of 65, so \[N = A - Z = 65 - 30 = 35\] Forming the dipositive ion removes two electrons; the nucleus is untouched, so the neutron count is unchanged.
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Among the given nutrients, milk is a poor source of
Answer: C
Milk is a poor source of vitamin C.
It is rich in calcium, high-quality protein and lactose, and supplies vitamins A, D and the B group, but contains very little ascorbic acid - and pasteurisation destroys most of what there is. This is why an infant fed only on milk needs a separate source of vitamin C.
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The ionic radii of N3-, O2-, F- and Na+ follows the order
Answer: A
The order is \(\mathrm{N^{3-} > O^{2-} > F^- > Na^+}\).
All four are isoelectronic, each having 10 electrons, so the size depends only on the nuclear charge pulling them in: \[\mathrm{N}\ (Z=7) < \mathrm{O}\ (8) < \mathrm{F}\ (9) < \mathrm{Na}\ (11)\] The larger the nuclear charge for the same electron count, the smaller the ion - so radius falls as \(Z\) rises.
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Glass is a.........mixture of metallic...........
Answer: B
Glass is a homogeneous mixture of metallic silicates.
Ordinary soda-lime glass is a fused mixture of sodium and calcium silicates in silica, of no fixed composition, and it is uniform throughout with no visible boundaries. Being amorphous, it has no sharp melting point.
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Symbol for silver in periodic table is
Answer: A
Silver's symbol is Ag.
It comes from the Latin argentum. Several symbols are Latin rather than English: Au from aurum for gold, Fe from ferrum, Na from natrium, K from kalium and Pb from plumbum.
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Which is also called Stranger Gas ?
Answer: C
Xenon is called the stranger gas.
The name comes from the Greek xenos, meaning stranger, and was given by Ramsay and Travers in 1898 because it was found only in vanishingly small traces in liquid air. It is also the noble gas that most readily forms compounds, such as \(\mathrm{XeF_4}\).
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Sugars are converted in the liver into
Answer: B
The liver converts sugars into glycogen.
Glucose absorbed from the gut is polymerised to glycogen and stored, a process called glycogenesis and driven by insulin. When blood glucose falls, glucagon reverses it and the glycogen is broken down again.
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