$T_m$ denotes the number of triangles that can be formed with the vertices of a regular polygon of $m$ sides. If $T_{m+1}-T_m=15$,then $m$ is equal to

In any fission process,the ratio $\frac{\text{mass of fission products}}{\text{mass of parent nucleus}}$ is

Which one of the following is not an essential mineral element for plants while the remaining three are?

Which of the following is an oxidizing agent?

$I$ carried $1000\,kg$ of watermelon in summer by train. In the beginning,the water content was $99\%$. By the time $I$ reached the destination,the water content had dropped to $98\%$. The reduction in the weight of the watermelon was $.......\,kg$.

Three processes form a thermodynamic cycle as shown on the $P-V$ diagram for an ideal gas. Process $1 \to 2$ takes place at a constant temperature $(300\,K)$. Process $2 \to 3$ takes place at a constant volume. During this process,$40\,J$ of heat leaves the system. Process $3 \to 1$ is adiabatic and the temperature $T_3$ is $275\,K$. The work done by the gas during the process $3 \to 1$ is...... $J$.