Thymine is .......

An ideal gas is expanding such that $PT^2 =$ constant. The coefficient of volume expansion of the gas is

Which of the following groups of organisms can interbreed?

Two particles which are initially at rest,move towards each other under the action of their internal attraction. If their speeds are $v$ and $2v$ at any instant,then the speed of the centre of mass of the system will be

Sodium metal crystallizes in a body-centred cubic $(bcc)$ lattice with a unit cell edge of $4.29 \ \mathring{A}$. The radius of the sodium atom is approximately: .............. $\mathring{A}$

For the reaction $2H_{(g)} \to H_{2_{(g)}}$,the signs of $\Delta H$ and $\Delta S$ are: