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10 g of radioactive material of half-life 15 year is kept in store for 20 years. The disintegrated material mass is
Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0, the number of P species are 4N_0 and that of Q is N_0. Half-life of P (for conversion to R) is 1 min whereas that of Q is 2 min. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be:
After two hours, one-sixteenth of the starting amount of a certain radioactive isotope remained undecayed. The half life of the isotope is
Floridean starch has structure similar to
For radioactive material, the half-life is 10 minutes. If initially, there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is:
A mass of $2.0\text{ kg}$ is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released, the mass executes a simple harmonic motion. The spring constant is $200\text{ N/m}$. What should be the minimum amplitude of the motion, so that the mass gets detached from the pan? (Take $g=10\text{ m/s}^2$)
The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an:
The intensity at the maximum in Young's double-slit experiment is $I_0$ when the distance between two slits is $d=5\lambda$, where $\lambda$ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance $D= 10d$?
The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be:
Which of the following hormone levels will cause release of ovum (ovulation) from the graffian follicle?
The SI unit of universal gas constant (R) is
At some instant, the number of radioactive atoms in a sample is $N_0$ and after time $t$, the number decreases to $N$. It is found that the graphical representation $\ln N$ versus $t$ along the $y$ and $x$ axis respectively is a straight line. Then the slope of this line is:
The half-life of a radioactive substance is 20 minutes. In how much time, the activity of substance drops to $(1/16)^{th}$ of its initial value?
The ratio of nuclear densities and nuclear volumes of ${}_{26}^{56}\mathrm{Fe}$ and ${}_{2}^{4}\mathrm{He}$ are, respectively:
At any instant, two elements $X_1$ and $X_2$ have the same number of radioactive atoms. If the decay constants of $X_1$ and $X_2$ are $10\lambda$ and $\lambda$ respectively, then the time when the ratio of their atoms becomes $1/e$ will be:
Which one of the following represents forward biased circuit?
Inspite of interspecific competition in nature, which mechanism the competing species might have evolved for their survival?
When gene targetting involving gene amplification is attempted in an individual's tissue to treat disease, it is known as :
Which of the following gate is called the universal gate?
Moss peat is used as a packing material for sending flowers and live plants to distant places because: