Why did oceans not exist on earth nearly 4 billion years ago?
a. no water molecules were present.
b. water remained a gas because earth was very hot.
c. water existed as ice because earth was very cold.
d. there was no oxygen gas in the atmosphere

Ahowler monkey is the loudest land animal and, under some circumstances, can be heard up to a distance of 4.6 km. assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10-12 w/m2. what is the acoustic power emitted by the howler

In positive numbers less than 1, the zeros between the decimal point and a non-zero number are blank significant

Which of the following are guidelines to follow for obtaining accurate observations