Recent questions tagged class12

There are two radioactive substance A and B . Decay constant of B is two times that of A . Initially both have equal no.of nuclei . After n Lay liver of A rate of disintegration of both are equal . The value of n is

asked Feb 24, 2014 by yamini.v

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The major product formed in the reaction given below is

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Among the following molecules:The increasing order of rate of cannizzaro reaction is

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If stationary proton and $\;\alpha-\;$ particle dre accelerated through same potential difference , the ratio of Debrogle's wavelength will be

asked Feb 24, 2014 by yamini.v

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The wavelength of $\;K_{\alpha}\;$ X-ray produced by X-ray to be is 0.76$A^{0}\;$. The atomic no.of anticathode material is

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What is the major product in the following reaction:

asked Feb 24, 2014 by sreemathi.v

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Predict the product in the below reaction:

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In the following reaction

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The major product of the following reaction is

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The ratio of minimum to maximum wavelengths of radiation that an electron cause in Bohr's hydrogen atom is

asked Feb 24, 2014 by yamini.v

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In the below reaction :The product X is

asked Feb 24, 2014 by sreemathi.v

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Radio isotopes of phosphorous $\;P^{32}\;$ and $\;P^{35}\;$ are mixed in ratio of 2:1 of atoms .The activity of samples 2 $\;\mu Ci\;$.Find activity of sample after 30 days. $\;t_{\large\frac{1}{2}}\;$ of $\;P^{32}=14\;$days and $\;t_{\large\frac{1}{2}}\;$ of $\;P^{33}\;$ is 25 days.

asked Feb 24, 2014 by yamini.v

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What would be the major product of the following reaction?

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The density of cr atoms is 7.2g/cm. If the unit cell has edge length 289 pm. Calculate the number of chromium atoms per unit cell. (at mass of cr = 52)

asked Feb 24, 2014 by sharmaaparna1

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The approriate reagents for the following transformation?

asked Feb 24, 2014 by sreemathi.v

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The mean lives of an radio active substance are 1620 and 405 years for $\;\alpha-\;$emission and $\;\beta-\;$ emission respee. Find out time during which three fourth of a sample will decay if it is decaying both the $\;\alpha-\;$emission and $\;\beta-\;$ emission simultaneously

asked Feb 24, 2014 by yamini.v

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In the below reaction :

asked Feb 24, 2014 by sreemathi.v

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Chromium metal crystallizes with a b.c.c lattice. The edge length of the unit cell is found to be 287pm. Calculate the density of chromium in $g\;cm^{-3}$(at weight of cr = 52).

asked Feb 24, 2014 by sharmaaparna1

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It is proposed to use nuclear fusion reaction : $\; _{1}H^{2}+_{1}H^{2}=\;_{2}He^{4}\;$ in a nuclear reactor of 200MW rating . If energy from above reaction is used with a $\;25 \%\;$ efficiency in reactor how many gr ams of deuterium will be needed per day . (The masses of $\;_{1}H^{2}\;$ and $\;_{2}He^{4}\;$ are 2.0141 & 4.0026 amu respectively

asked Feb 24, 2014 by yamini.v

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What would be the product of the following reaction?

asked Feb 24, 2014 by sreemathi.v

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Product of below reaction will be

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uranium ores on earth at present time typically have a composition of $\;99.3 \%$ of isotope $\;_{92}U^{238}\;$ and $\;0.7 \%\;$ of isotope $\;_{92}U^{235}\;$. The half lives of these isotopes are $\;4.47 \times10^{9}y\;$ and $\;7.04\times10^{8}y\;$ respectively . If these isotopes were equally abundent when the earth was formed , estimate the age of earth .

asked Feb 24, 2014 by yamini.v

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The product of the below reaction:

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In the following reaction the major product formed is a

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The activity of a radiooctine sample is measured as 4750 counts/min at $\;t=0\;$ and as 2700 counts/min at $\;t=5$ minutes . Calculate Lay life of sample

asked Feb 24, 2014 by yamini.v

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A deuterium reaction that occurs in an experimental fusion reactor is in two stapes \[\] (1) Two deuterium nucli fuse together to form a tritium nucleus , with a proton as a by-product written as $\; 1 > (D ,P)\; T\;.$ \[\] (2) A tritium nucleus fuses with another oleunterium nucleus to form a helium $\;_{2}He^{4}\;$ nucleus with neutron as a-by-product written as $\;T (D,n)\;_{2}He^{4}\;.$ Then the energy released in each of two stages and energy released in combined reaction is \[\] Given \[\] $\;_{1}D^{2}=2.014102\;a.m.u $ \[\] $\;_{1}T^{3}=3.016049\;a.m.u$ \[\] $\;_{1}H^{1}=1.007825\;a.m.u$ \[\] $\;_{1}n^{1}=1.008665\;a.m.u$\[\] The energy released per deuterium nuclei is

asked Feb 24, 2014 by yamini.v

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Which is a product of Y of the following reaction:

asked Feb 24, 2014 by sreemathi.v

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