Which of the following are plant growth promoters?

Name a hormone which:
$(A)$ is gaseous in nature
$(B)$ is responsible for phototropism
$(C)$ induces femaleness in flowers of cucumber
$(D)$ is used for killing weeds (dicots)
$(E)$ induces flowering in long day plants

Polyploidy can be induced by the application of

The following statements are given about plant growth hormones:
$I.$ Cytokinins suppress the synthesis of chlorophyll.
$II.$ Auxins control apical dominance.
$III.$ Gibberellins promote shoot elongation.
$IV.$ Abscisic acid enables seeds to withstand desiccation.
Which of the above statements are correct?

One hormone hastens the maturity period in juvenile conifers,a second hormone controls xylem differentiation,while the third increases the tolerance of plants to various stresses. They are respectively:

What is the role of light in plants?