The surface tension of a liquid

Assume that, positrons $\left(e^{+}\right)$produced in the decay combine with free electrons in the atmosphere and annihilate each other almost immediately. Also, assume that the neutrinos $\left(v_e\right)$ are massless and do not interact with the environment. At $t=0$, we have $1 \mu g$ of ${ }_6^{12} C$. If the half-life of the decay process is $t_0$, the net energy produced between time $t=0$ and $t=2 t_0$, will be nearly ........... $MeV$

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If the total binding energies of ${ }_1^2 H ,{ }_2^4 He ,{ }_{26}^{56} Fe$ and ${ }_{92}^{235} U$ nucleiare $2.22,28.3,492$ and $1786 MeV$ respectively, identify the most stable nucleus of the following.

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The Fraunhoffer ‘diffraction’ pattern of a single slit is formed in the focal plane of a lens of focal length $1\,m$. The width of slit is $0.3\,mm$. If third minimum is formed at a distance of $5\,mm$ from central maximum, then wavelength of light will be......$\mathop A\limits^o $

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A particle is projected vertically upwards from $O$ with velocity $v$ and a second particle is projected at the same instant from $P$ (at a height h above $O$) with velocity $v$ at an angle of projection $\theta$ . The time when the distance between them is minimum is

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If $n$ represents the actual number of deflections in a converted galvanometer of resistance $G$ and shunt resistance $S$. Then the total current I when its figure of merit is $K$ will be

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A bomb is released from a horizontal flying aeroplane. The trajectory of bomb is

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A $60 \,kg$ weight is dragged on a horizontal surface by a rope upto $ 2$ metres. If coefficient of friction is $\mu = 0.5$, the angle of rope with the surface is $60^°$ and $g = 9.8\,m/{\sec ^2}$, then work done is ........ $joules$