The whorl of bracts present below the inflorescence of $Helianthus$ $(sunflower)$ is

An inductance $L$ having a resistance $R$ is connected to an alternating source of angular frequency $\omega$. The Quality factor $Q$ of the inductance is

Assertion : $NF_3$ is a weaker ligand than $N(CH_3)_3$.
Reason : $NF_3$ ionizes to give $F^-$ ions in aqueous solution.

If the equation of the locus of a point equidistant from the points $(a_1, b_1)$ and $(a_2, b_2)$ is $(a_1 - a_2)x + (b_1 - b_2)y + c = 0$,then the value of $c$ is

For the reaction $2NO_2 + F_2 \to 2NO_2F$,the following mechanism has been provided:
$NO_2 + F_2 \xrightarrow{slow} NO_2F + F$
$NO_2 + F \xrightarrow{fast} NO_2F$
Thus,the rate expression of the above reaction can be written as:

Two uniform strings $A$ and $B$ made of steel are made to vibrate under the same tension. If the first overtone of $A$ is equal to the second overtone of $B$ and if the radius of $A$ is twice that of $B,$ the ratio of the lengths of the strings is