What does green manure provide?

$A$ reversible engine converts one-sixth of the heat supplied into work. When the temperature of the sink is reduced by $62^{\circ} C$,the efficiency of the engine is doubled. The temperatures of the source and sink are

Which of the following is a fossil pteridophyte?

In a playground,there is a merry-go-round of mass $120 \ kg$ and radius $4 \ m$. The radius of gyration is $3 \ m$. $A$ child of mass $30 \ kg$ runs at a speed of $5 \ m/s$ tangent to the rim of the merry-go-round when it is at rest and then jumps on it. Neglecting friction,find the angular velocity of the merry-go-round and child in $rad/s$.

Consider telecommunication through optical fibres. Which of the following statements is $NOT$ true?

An $LCR$ series circuit with a resistance of $100\,\Omega$ is connected to an ac source of $200\,V$ (r.m.s.) and angular frequency $300\,rad/s$. When only the capacitor is removed,the current lags behind the voltage by $60^\circ$. When only the inductor is removed,the current leads the voltage by $60^\circ$. The average power dissipated is......$W$.