The length of an elastic string is $a \, m$ when the longitudinal tension is $4 \, N$ and $b \, m$ when the longitudinal tension is $5 \, N$. The length of the string in metres when the longitudinal tension is $9 \, N$ is

Ecdysone is produced by

For a given material,the Young's modulus is $2.4$ times that of the rigidity modulus. Its Poisson's ratio is

The reaction sequence given below is carried out with $16$ moles of $X$. The yield of the major product in each step is given below the product in parentheses. The amount $($in grams$)$ of $S$ produced is $.....$
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Use: Atomic mass $($in amu$): H =1, C =12, O =16, Br =80$

If the imaginary part of $\frac{2z+1}{iz+1}$ is $-2$,then the locus of the point representing $z$ in the Argand plane is

The collector plate in an experiment on the photoelectric effect is kept vertically above the emitter plate. $A$ light source is turned on,and a saturation photocurrent is recorded. An electric field is then switched on,which has a vertically downward direction.