Answer:
4.5 billion years ago
Earth hasn't always been a blue and green oasis of life in an otherwise inhospitable solar system. During our planet's first 50 million years, around 4.5 billion years ago, its surface was a hellscape of magma oceans, bubbling and belching with heat from Earth's interior.
Explanation:
In meiosis, the chromosome pairs do the crossing over where there is an exchange of genetic material between them and because of it the
chromatids held together by the centromere are no longer the same.
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:
