The figure shows wave fronts in still water,moving in the direction of the arrow towards the interface $PQ$ between a shallow region and a deep (denser) region. Which of the lines shown may represent one of the wave fronts in the deep region?

Which of the following is a herbicide?

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.

Two cards are drawn successively with replacement from a well-shuffled pack of $52$ cards. The mean of the number of kings is:

If $f:[2, \infty) \rightarrow B$ defined by $f(x)=x^2-4x+5$ is a bijection,then $B$ is equal to

The angle between the straight lines $x^2+4xy+y^2=0$ is....... (in $^{\circ}$)