Tadpoles have gills allowing them to breathe underwater while frogs have lungs. Tadpoles have tails and fins to help them swim while frogs have arms and legs.
Answer:
Q2->They all form acids when combined with hydrogen. They are all fairly toxic. They readily combine with metals to form salts.
Q3->Because their outermost orbit is complete. In Mendeleev's original periodic table there was no place reserved for noble gas. They were discovered in end of 19th century. So Mendeleev created zero group without disturbing original periodic table.
Explanation:
A. Osmosis. Hope this helps :)
