If the coordinate axes are the bisectors of the angles between the pair of lines $ax^2 + 2hxy + by^2 = 0$ where $h^2 > ab$ and $a \neq b$,then

Which of the following $statement(s)$ is/are correct?
$(i)$ All living organisms have the ability to respond to environmental stimuli,which could be physical,chemical,or biological.
$(ii)$ Plants respond to external factors like light,water,temperature,other organisms,pollutants,etc.
$(iii)$ Photoperiod affects the process of reproduction.
$(iv)$ Human being is the only organism who has self-consciousness.

If $a \cdot \hat{i} = a \cdot (\hat{i} + \hat{j}) = a \cdot (\hat{i} + \hat{j} + \hat{k})$,then $a$ is equal to

$A$ sinusoidal carrier voltage of frequency $1.5 \, MHz$ and amplitude $50 \, V$ is amplitude modulated by a sinusoidal voltage of frequency $10 \, kHz$ producing $50 \% $ modulation. The lower and upper side-band frequencies in $kHz$ are:

The focal length of a mirror is given by $\frac{2}{f} = \frac{1}{v} - \frac{1}{u}$. In finding the values of $u$ and $v$,the errors are equal to $p$. Then,the relative error in $f$ is