Two rods of the same length and material transfer a given amount of heat in $12 \, s$,when they are joined in parallel. But when they are joined in series,then they will transfer the same amount of heat under the same conditions in ......... $s$.

The binding energy of deuteron ${}_1^2H$ is $1.112 \, MeV$ per nucleon and an $\alpha$-particle ${}_2^4He$ has a binding energy of $7.047 \, MeV$ per nucleon. Then in the fusion reaction ${}_1^2H + {}_1^2H \to {}_2^4He + Q$,the energy $Q$ released is ......... $MeV$.

Which of the following compounds will exhibit geometrical isomerism?

The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true?

If $R$ is the radius of the Earth and $g$ is the acceleration due to gravity on the Earth's surface,then the mean density of the Earth is ..........

The sound waves of wavelengths $5 ~m$ and $6 ~m$ produce $30$ beats in $3 ~s$. The velocity of sound is: (in $~m/s$)