Which of the following respiratory organs are present in spiders and scorpions?

Given below are four matchings of an animal and its kind of respiratory organ:
$I.$ Silver fish - Trachea
$II.$ Scorpion - Book lung
$III.$ Sea squirt - Pharyngeal gills
$IV.$ Dolphin - Skin
The correct matchings are:

Submerged hydrophytes exchange gases through

Which of the following modes of respiration always continues in a frog?

With respect to the respiratory apparatus,pick out the incorrect pair/pairs.

Which animal among the following respires via buccal cavity,moist skin and lungs?