In an atomic explosion, enormous energy is released which is due to
Answer: C
The energy of an atomic explosion comes from the conversion of mass into energy.
The fragments of a fissioned uranium nucleus weigh slightly less than the original, and the missing mass appears as energy according to Einstein's relation:
\[ E = mc^2 \]
Because \( c^2 \) is so large, a gram of mass yields about 9 × 1013 joules.
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Noise, or noise pollution, is measured in
Answer: C
The decibel measures the loudness or intensity of sound.
It is logarithmic: 10 dB is a tenfold increase in intensity, so the scale can cover the enormous range the ear handles. Frequency, which determines pitch, is measured in hertz instead - cycles per second.
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Which amongst the following is not true about the chandrayan1?
Answer: B
The false statement is the rocket's serial number: Chandrayaan-1 was launched by PSLV-XL C11, not C13.
The other statements are correct. It was launched by ISRO in October 2008, entered lunar orbit on 8 November 2008, and the project had been announced by Prime Minister Vajpayee on 15 August 2003.
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Where does the cabbage store food?
Answer: D
The cabbage stores its food in the leaves. The head is a tight rosette of thickened, overlapping leaves packed with reserves.
Cauliflower stores food in the flower head, potato in the stem tuber and carrot in the root.
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Brass gets discoloured in air because of the presence of which of the following gases in air?
Answer: B
Brass discolours in air because of hydrogen sulphide, which reacts with the copper in the alloy to form a dark film of copper sulphide.
The gas is present in traces in polluted air and near decaying organic matter. Silver tarnishes black for exactly the same reason.
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One fathom is equal to how many meters ?
Answer: C
One fathom is 1.8288 m, exactly 6 feet.
\[ 6 \times 0.3048 = 1.8288\ \mathrm{m} \]
The unit is used for the depth of water and comes from the Old English for the span of a man's outstretched arms.
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The oxide of Nitrogen used in medicine as anaesthetic is
Answer: C
Nitrous oxide (N2O) is the oxide of nitrogen used as an anaesthetic. Known as laughing gas, it has been used in dentistry and surgery since the 1840s.
Nitric oxide and nitrogen dioxide are toxic, and nitrogen pentoxide is an unstable solid that reacts violently with water - none of them could be breathed.
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Which animal never drinks water in its entire life?
Answer: C
The kangaroo rat of the North American deserts never drinks. It gets all the water it needs from the metabolic breakdown of the dry seeds it eats.
It survives by losing almost none: it has no sweat glands, produces extremely concentrated urine and nearly dry droppings, and recovers moisture from its own breath in its nasal passages.
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Stains Of rust on clothes can be removed by -
Answer: D
Rust stains are removed with oxalic acid.
It reduces the insoluble iron(III) of the rust and forms a soluble complex with it, so the stain washes out of the fabric. Lemon juice and salt work more slowly by the same principle.
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Heavy water is:
Answer: A
Heavy water is deuterium oxide, D2O, in which both hydrogen atoms are the heavier isotope with a proton and a neutron.
It occurs naturally as about one part in 6,400 of ordinary water and is about 11 per cent denser. Because it absorbs very few neutrons it is used as a moderator in nuclear reactors, including India's PHWRs.
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